Animal Galls, Produced by Breeze-Flies and Snail-Beetles 424
Grub Parasite in the Snail 436
ILLUSTRATIONS.
PAGE
1. Eggs of Insects, magnified 16
2. Larvæ 17
3. Pupæ 18
4. Insects in the Imago or perfect state 19
5. Mason-Wasp 23
6. Jaws of Mason-Wasp 24
7. Cuckoo-Fly 25
8. Mason-Wasp's Nest and Cocoons 25
9. Mason-Wasp 25
10. Nests, &c., of Mason-Wasps 26
11. Towers built by Mason-Wasp 29
12. Nests of _Pompilus punctum_ 29
13. _Scolia Xantiana_, and section of its burrow 35
14. Mason-Bee 38
15. Exterior wall of Mason-Bee's Nest 39
16. Cells of a Mason-Bee 39
17. Cells of Mason-Bees 46
18. Cells of _Chalicodoma_ 49
19. Nest of _Synagris calida_ 50
20. Cell of Mining-Bee 51
21. Cells of Carpenter-Bees, in an old post 57
22. Carpenter-Bee and Cells 58
23. Carpenter-Wasp and Cells 62
24. Rose-leaf-cutter-Bee and Nest 71
25. Carder-Bee and Nest 75
26. Breeding-cells of Carder-Bee 77
27. Interior view of Carder-Bee's Nest 78
28. Cells of Humble-Bee and Insects 80
29. Nest of Common Wasp in early stage 88
30. Section of Wasp's Nest 89
31. Section of Social-Wasps' Nest 90
32. Suspension-rod and part of external crust of
Social-Wasps' Nest 91
33. Hornet's Nest in its first stage 92
34. Complete Hornet's Nest, and Insect 93
35. Hornet's Nest in hollow tree 94
36. Nest of Tree-Wasp 96
37. Wasp's Nest 97
38. Wasps' Cells attached to a branch 98
39. Comb of _Polistes_ 99
40. Nest of the Pasteboard-maker Wasp 103
41. Nest of _Myrapetra_ 105
42. Nests of _Polybia_ 108
43. Nests of _Synæca_ and _Polybia_ 109
44. Part of a Honeycomb and Bees at work 112
45. Worker-Bee, magnified 123
46. Abdomen of Wax-worker Bee 124
47. Structure of the Legs of the Bee 130
48. Curtain of Wax-workers secreting wax 133
49. Wax-worker laying the foundation of first cell 136
50. Curtain of Wax-workers 137
51. Arrangement of Cells 141
52. Foundation-wall and Cells commenced 143
53. Hive-Bees and Cells 159
54. Ovipositors, with files, of Tree-hopper 167
55. Excavations for eggs of Tree-hopper 167
56. Ovipositor of Saw-Fly 169
57. Ovipositor of Saw-Fly, much magnified 170
58. Portion of Saw-Fly's comb-toothed rasp 171
59. Nest of eggs of Saw-Fly 173
60. Saw-Fly of the gooseberry 174
61. Exterior and section of Nest of _Deilocenes Ellisii_,
and Insect 176
62. Cells of _Icaria_ 177
63. Cells of _Raphigaster Guiniensis_ 178
64. Single Cells of _Icaria_ 179
65. Lilac-tree Moth 182
66. Nest of Lilac-leaf-roller 182
67. Do. another specimen 183
68. Small green Oak-Moth 184
69. Nests of Oak-leaf-rolling Caterpillars 184
70. Nest of Nettle-leaf-rolling Caterpillar 186
71. Leaf-rolling Caterpillars of the sorrel 188
72. Nests of the _Hesperia Malvæ_ with Caterpillar, Chrysalis,
and Butterflies 189
73. Nest of Willow-leaf-roller 191
74. Ziczac Caterpillar and Nest 192
75. Cypress-Spurge Caterpillar 198
76. Moss-cell of small Caterpillar 200
77. Leaf-nest of Caddis-Worm 202
75. Reed-nest of Caddis-Worm 202
79. Cell of _Phryganea_ 203
80. Shell-nests of Caddis-Worms 203
81. Stone-nest of Caddis-Worm 204
82. Sand-nest balanced with a stone 204
83. Nest of Caddis-Worm balanced with straws 204
84. Various Nests of Caddis-Worms 206
85. Caterpillar of Goat-Moth 208
86. Winter-nest of Goat-Caterpillar 208
87. Nest of Goat-Moth 209
88. Larva of _Ægeria_ 211
89. Eggs of the Puss-Moth 213
90. Rudiments of the Cell of Puss-Moth 213
91. Cell of Larva of Puss-Moth 214
92. Ichneumon 215
93. Magnified Cells of _Pyralis strigulalis_ (?) 217
94. Outside view of Nests of Earth-Mason Caterpillars 220
95. Nests, etc., of Earth-Mason Caterpillar 221
96. Do. with perfect Moth 223
97. Nests of the Grubs of _Ephemeræ_ 225
98. Nests of _Ephemeræ_ in holes of Cossus 225
99. Grub of the Ant-Lion with traps 228
100. Ant-Lion's traps in experimenting-box 231
101. Cases of the Clothes-Moth and Insect 238
102. Transformations of the Honeycomb-Moths 240
103. Transformations of the Grain-Moths 242
104. Tent of Caterpillar upon elm-leaf 244
105. Operations of Caterpillar upon leaf 246
106. Lichen-tents and Caterpillars 247
107. Branch of willow with Caterpillars' muff-tents 251
108. Rose-leaf mined by Caterpillars 253
109. Bramble-leaf do. 254
110. Primrose-leaf do. 255
111. Bark mined by Beetle-Grubs 259
112. Cocoons of _Rhagium_ and _Rhyncophorus_ 261
113. Capricorn-Beetle rounding off bark of tree 262
114. _Cerambyx carcharias,_ and _Cerambyx populneus_ 263
115. The Mole-Cricket 265
116. Nest of Mole-Cricket 266
117. _Acrida Verrucivora_ depositing her eggs 269
118. Transformations of the Cockchafer 276
119. Ant-hive or Formicary 291
120. Floor of Ant-nest 292
121. Insecure Nest propped up by Ants 293
122. Nest of Wood-Ant 295
123. Artificial Formicary 298
124. Portion of a tree tunnelled by Jet Ants 302
125. _Formica fuliginosa_ 304
126. _Crematogaster_ 310
127. Nests of _Polyrachis bispinosa_ and _P. textor_ 311
128. _Termes bellicosus_ in the winged state 317
129. Queen Termite distended with eggs 320
130. Tree-nest of _Termites arborum_, and Hill-nests of
_T. bellicosus_ 324
131. Turret-nests of White Ants 326
132. Leg and Pro-leg of Caterpillar 331
133. Caterpillar of Goat-Moth 332
134. Interior structure of Cossus 333
135. Side view and section of Silk-tube of Cossus 334
136. Labium of Cossus 334
137. Cocoons of Emperor-Moth 343
138. Cocoon of _Arctia villica_ 345
139. Net-work Cocoon 345
140. Nest of Puss-Moth 347
141. Caterpillars of small Ermine on Siberian crab 351
142. Winter-nests of _Porthesia chrysorrhoea_ 352
143. Winter-nests of Social Caterpillars 353
144. Pendulous Leaves 356
145. Nest of _Larrada_ 357
146. Nests of _Polybia_ 358
147. Nests of _Oiketicus_, &c. 359
148. Nests of _Pelopæus_, &c. 361
149. _Bombycidæ_ 363
150. Processionary Caterpillars 364
151. Nest of do. 365
152. Garden Spider suspended by single thread 367
153. Spinnerets of Spiders 368
154. Single thread of Spider, greatly magnified 369
155. Attached end of Spider's thread 369
156. Geometric Net of _Epeira diadema_ 387
157. Nest of the Mason-Spider 389
158. Nest of _Mygale sauvagesii_ 391
159. Insect emerging from its Nest 391
160. Triple-clawed Foot of Spider 395
161. Small Galls on Oak-leaf 398
162. Ovipositor of Gall-Fly 399
163. Gall-Fly and mechanism of ovipositor 400
164. Bedeguar Gall of the Rose 402
165. One of the bristles of Bedeguar, magnified 403
166. Artichoke Gall of the Oak-bud, and Insect 405
167. Leafy gall of Dyer's Broom 406
168. Semi-gall of the Hawthorn 408
169. Woolly Gall of the Oak 409
170. Oak-apple Galls 410
171. Root-galls of the Oak 411
172. Woody Gall on a Willow Branch 412
173. Currant-gall of the catkins of the Oak 413
174. Gall of the Hawthorn-Weevil 414
175. Plant-Louse, magnified 416
176. Galls produced on the Poplar, and Insects 417
177. Leaf of the Currant-bush with Aphides 419
178. Shoot of Lime-tree contorted by _A. tiliæ_ 421
179. Pseudo-gall of the Bramble 422
180. Pseudo-galls of the Hawthorn 423
181. Ovipositor of the Breeze-Fly 426
182. The Grub of Breeze-Fly 432
183. The Ox-Breeze-Fly 433
184. Bumps produced on cattle by Breeze-Fly 434
185. _Microgaster glomeratus_ 438
186. _Microgaster alveolarius_ 439
INSECT ARCHITECTURE.
_CHAPTER 1._
INTRODUCTION.
It can never be too strongly impressed upon a mind anxious for the
acquisition of knowledge, that the commonest things by which we are
surrounded are deserving of minute and careful attention. The most
profound investigations of Philosophy are necessarily connected
with the ordinary circumstances of our being, and of the world in
which our every-day life is spent. With regard to our own existence,
the pulsation of the heart, the act of respiration, the voluntary
movement of our limbs, the condition of sleep, are among the most
ordinary operations of our nature; and yet how long were the wisest
of men struggling with dark and bewildering speculations before they
could offer anything like a satisfactory solution of these phenomena,
and how far are we still from an accurate and complete knowledge of
them! The science of Meteorology, which attempts to explain to us the
philosophy of matters constantly before our eyes, as dew, mist, and
rain, is dependent for its illustrations upon a knowledge of the most
complicated facts, such as the influence of heat and electricity upon
the air; and this knowledge is at present so imperfect, that even these
common occurrences of the weather, which men have been observing and
reasoning upon for ages, are by no means satisfactorily explained, or
reduced to the precision that every science should aspire to. Yet,
however difficult it may be entirely to comprehend the phenomena we
daily witness, everything in nature is full of instruction. Thus the
humblest flower of the field, although, to one whose curiosity has
not been excited, and whose understanding has, therefore, remained
uninformed, it may appear worthless and contemptible, is valuable to
the botanist, not only with regard to its place in the arrangement of
this portion of the Creator's works, but as it leads his mind forward
to the consideration of those beautiful provisions for the support of
vegetable life, which it is the part of the physiologist to study and
to admire.
This train of reasoning is peculiarly applicable to the economy of
insects. They constitute a very large and interesting part of the
animal kingdom. They are everywhere about us. The spider weaves his
curious web in our houses; the caterpillar constructs his silken cell
in our gardens; the wasp that hovers over our food has a nest not
far removed from us, which she has assisted to build with the nicest
art; the beetle that crawls across our path is also an ingenious and
laborious mechanic, and has some curious instincts to exhibit to those
who will feel an interest in watching his movements; and the moth that
eats into our clothes has something to plead for our pity, for he came,
like us, naked into the world, and he has destroyed our garments,
not in malice or wantonness, but that he may clothe himself with the
same wool which we have stripped from the sheep. An observation of
the habits of these little creatures is full of valuable lessons,
which the abundance of the examples has no tendency to diminish. The
more such observations are multiplied, the more are we led forward
to the freshest and the most delightful parts of knowledge; the more
do we learn to estimate rightly the extraordinary provisions and
most abundant resources of a creative Providence; and the better do
we appreciate our own relations with all the infinite varieties of
nature, and our dependence, in common with the ephemeron that flutters
its little hour in the summer sun, upon that Being in whose scheme
of existence the humblest as well as the highest creature has its
destined purposes. "If you speak of a stone," says St. Basil, one of
the Fathers of the Church, "if you speak of a fly, a gnat, or a bee,
your conversation will be a sort of demonstration of His power whose
hand formed them, for the wisdom of the workman is commonly perceived
in that which is of little size. He who has stretched out the heavens,
and dug up the bottom of the sea, is also He who has pierced a passage
through the sting of the bee for the ejection of its poison."
If it be granted that making discoveries is one of the most
satisfactory of human pleasures, then we may without hesitation
affirm, that the study of insects is one of the most delightful
branches of natural history, for it affords peculiar facilities for
its pursuit. These facilities are found in the almost inexhaustible
variety which insects present to the curious observer. As a proof
of the extraordinary number of insects within a limited field of
observation, Mr. Stephens informs us, that in the short space of forty
days, between the middle of June and the beginning of August, he
found, in the vicinity of Ripley, specimens of above two thousand four
hundred species of insects, exclusive of caterpillars and grubs,--a
number amounting to nearly a fourth of the insects ascertained to be
indigenous. He further tells us, that, among these specimens, although
the ground had, in former seasons, been frequently explored, there
were about one hundred species altogether new, and not before in any
collection which he had inspected, including several new genera;
while many insects reputed scarce were in considerable plenty.[A] The
localities of insects are, to a certain extent, constantly changing;
and thus the study of them has, in this circumstance, as well as in
their manifold abundance, a source of perpetual variety. Insects, also,
which are plentiful one year, frequently become scarce, or disappear
altogether, the next--a fact strikingly illustrated by the uncommon
abundance, in 1826 and 1827, of the seven-spot lady-bird (_Coccinella
septempunctata_), in the vicinity of London, though during the two
succeeding summers this insect was comparatively scarce, while the
small two-spot lady-bird (_Coccinella bipunctata_) was plentiful.
There is, perhaps, no situation in which the lover of nature and the
observer of animal life may not find opportunities for increasing his
store of facts. It is told of a state prisoner, under a cruel and
rigorous despotism, that when he was excluded from all commerce with
mankind, and was shut out from books, he took an interest and found
consolation in the visits of a spider; and there is no improbability
in the story. The operations of that persecuted creature are among the
most extraordinary exhibitions of mechanical ingenuity; and a daily
watching of the workings of its instinct would beget admiration in
a rightly-constituted mind. The poor prisoner had abundant leisure
for the speculations in which the spider's web would enchain his
understanding. We have all of us, at one period or other of our lives,
been struck with some singular evidence of contrivance in the economy
of insects, which we have seen with our own eyes. Want of leisure, and
probably want of knowledge, have prevented us from following up the
curiosity which for a moment was excited. And yet some such accident
has made men naturalists, in the highest meaning of the term. Bonnet,
evidently speaking of himself, says, "I knew a naturalist, who, when
he was seventeen years of age, having heard of the operations of the
ant-lion, began by doubting them. He had no rest till he had examined
into them: and he verified them, he admired them, he discovered new
facts, and soon became the disciple and the friend of the Pliny of
France"[B] (Réaumur). It is not the happy fortune of many to be able to
devote themselves exclusively to the study of nature, unquestionably
the most fascinating of human employments; but almost every one may
acquire sufficient knowledge to be able to derive a high gratification
from beholding the more common operations of animal life. His materials
for contemplation are always before him. Some weeks ago we made an
excursion to West Wood, near Shooter's Hill, expressly for the purpose
of observing the insects we might meet with in the wood: but we had
not got far among the bushes, when heavy rain came on. We immediately
sought shelter among the boughs of some thick underwood, composed of
oak, birch, and aspen; but we could not meet with a single insect, not
even a gnat or a fly, sheltered under the leaves. Upon looking more
narrowly, however, into the bushes which protected us, we soon found
a variety of interesting objects of study. The oak abounded in galls,
several of them quite new to us; while the leaves of the birch and
the aspen exhibited the curious serpentine paths of the minute mining
caterpillars. When we had exhausted the narrow field of observation
immediately around us, we found that we could considerably extend it,
by breaking a few of the taller branches near us, and then examining
their leaves at leisure. In this manner two hours glided quickly and
pleasantly away, by which time the rain had nearly ceased; and though
we had been disappointed in our wish to ramble through the wood, we
did not return without adding a few interesting facts to our previous
knowledge of insect economy.[C]
It will appear, then, from the preceding observations, that cabinets
and collections, though undoubtedly of the highest use, are by no
means indispensable, as the observer of nature may find inexhaustible
subjects of study in every garden and in every hedge. Nature has
been profuse enough in affording us materials for observation, when
we are prepared to look about us with that keenness of inquiry,
which curiosity, the first step in the pursuit of knowledge, will
unquestionably give. Nor shall we be disappointed in the gratification
which is thus within our reach. Were it no more, indeed, than a
source of agreeable amusement, the study of insects comes strongly
recommended to the notice of the well-educated. The pleasures of
childhood are generally supposed to be more exquisite, and to contain
less alloy, than those of riper years; and if so, it must be because
then everything appears new and dressed in fresh beauties: while in
manhood, and old age, whatever has frequently recurred begins to wear
the tarnish of decay. The study of nature affords us a succession of
"ever-new delights," such as charmed us in childhood, when everything
had the attractions of novelty and beauty; and thus the mind of the
naturalist may have its own fresh and vigorous thoughts, even while the
infirmities of age weigh down the body.
It has been objected to the study of insects, as well as to that of
Natural History in general, that it tends to withdraw the mind from
subjects of higher moment; that it cramps and narrows the range of
thought; and that it destroys, or at least weakens, the finer creations
of the fancy. Now, we should allow this objection in its fullest
extent, and even be disposed to carry it further than is usually done,
if the collecting of specimens only, or, as the French expressly
call them, chips (_échantillons_), be called a study. But the mere
collector is not, and cannot be, justly considered as a naturalist;
and, taking the term naturalist in its enlarged sense, we can adduce
some distinguished instances in opposition to the objection. Rousseau,
for example, was passionately fond of the Linnæan botany, even to the
driest minutiæ of its technicalities; and yet it does not appear to
have cramped his mind, or impoverished his imagination. If Rousseau,
however, be objected to as an eccentric being, from whose pursuits no
fair inference can be drawn, we give the illustrious example of Charles
James Fox, and may add the names of our distinguished poets, Goldsmith,
Thomson, Gray, and Darwin, who were all enthusiastic naturalists. We
wish particularly to insist upon the example of Gray, because he was
very partial to the study of insects. It may be new to many of our
readers, who are familiar with the 'Elegy in a Country Churchyard,' to
be told that its author was at the pains to turn the characteristics
of the Linnæan orders of insects into Latin hexameters, the manuscript
of which is still preserved in his interleaved copy of the 'Systema
Naturæ.' Further, to use the somewhat exaggerated words of Kirby and
Spence, whose work on Entomology is one of the most instructive and
pleasing books on the science, 'Aristotle among the Greeks, and Pliny
the Elder among the Romans, may be denominated the fathers of Natural
History, as well as the greatest philosophers of their day; yet both
these made insects a principal object of their attention: and in more
recent times, if we look abroad, what names greater than those of Redi,
Malpighi, Vallisnieri, Swammerdam, Leeuwenhoek, Réaumur, Linnæus, De
Geer, Bonnet, and the Hubers? and at home, what philosophers have done
more honour to their country and to human nature than Ray, Willughby,
Lister, and Derham? Yet all these made the study of insects one of
their most favourite pursuits."[D]
And yet this study has been considered, by those who have superficially
examined the subject, as belonging to a small order of minds; and the
satire of Pope has been indiscriminately applied to all collectors,
while, in truth, it only touches those who mistake the means of
knowledge for the end:--
"O! would the sons of men once think their eyes
And reason given them but to study Flies!
See Nature, in some partial, narrow shape,
And let the Author of the whole escape;
Learn but to trifle; or, who most observe,
To wonder at their Maker, not to serve."[E]
Thus exclaims the Goddess of Dulness, sweeping into her net all those
who study nature in detail. But if the matter were rightly appreciated,
it would be evident that no part of the works of the Creator can be
without the deepest interest to an inquiring mind; and that a portion
of creation which exhibits such extraordinary manifestations of design
as is shown by insects must have attractions for the very highest
understanding.
An accurate knowledge of the properties of insects is of great
importance to man, merely with relation to his own comfort and
security. The injuries which they inflict upon us are extensive and
complicated; and the remedies which we attempt, by the destruction of
those creatures, both insects, birds, and quadrupeds, who keep the
ravages in check, are generally aggravations of the evil, because they
are directed by an ignorance of the economy of nature. The little
knowledge which we have of the modes by which insects may be impeded
in their destruction of much that is valuable to us, has probably
proceeded from our contempt of their individual insignificance. The
security of property has ceased to be endangered by quadrupeds of
prey, and yet our gardens are ravaged by aphides and caterpillars. It
is somewhat startling to affirm that the condition of the human race
is seriously injured by these petty annoyances; but it is perfectly
true that the art and industry of man have not yet been able to
overcome the collective force, the individual perseverance, and the
complicated machinery of destruction which insects employ. A small ant,
according to a most careful and philosophical observer, opposes almost
invincible obstacles to the progress of civilization in many parts
of the equinoctial zone. These animals devour paper and parchment;
they destroy every book and manuscript. Many provinces of Spanish
America cannot, in consequence, show a written document of a hundred
years' existence. "What development," he adds, "can the civilization
of a people assume, if there be nothing to connect the present with
the past--if the depositories of human knowledge must be constantly
renewed--if the monuments of genius and wisdom cannot be transmitted
to posterity?"[F] Again, there are beetles which deposit their larvæ
in trees in such formidable numbers that whole forests perish beyond
the power of remedy. The pines of the Hartz have thus been destroyed
to an enormous extent; and in North America, at one place in South
Carolina, at least ninety trees in every hundred, upon a tract of two
thousand acres, were swept away by a small black, winged bug. And
yet, according to Wilson, the historian of American birds, the people
of the United States were in the habit of destroying the redheaded
woodpecker, the great enemy of these insects, because he occasionally
spoilt an apple.[G] The same delightful writer and true naturalist,
speaking of the labours of the ivory-billed woodpecker, says, "Would
it be believed that the larvæ of an insect or fly, no larger than
a grain of rice, should silently, and in one season, destroy some
thousand acres of pine-trees, many of them from two to three feet in
diameter, and a hundred and fifty feet high? In some places the whole
woods, as far as you can see around you, are dead, stripped of the
bark, their wintry-looking arms and bare trunks bleaching in the sun,
and tumbling in ruins before every blast."[H] The subterraneous larva
of some species of beetle has often caused a complete failure of the
seed-corn, as in the district of Halle in 1812.[I] The corn-weevil,
which extracts the flour from grain, leaving the husk behind, will
destroy the contents of the largest storehouses in a very short period.
The wire-worm and the turnip-fly are dreaded by every farmer. The
ravages of the locust are too well known not to be at once recollected
as an example of the formidable collective power of the insect race.
The white ants of tropical countries sweep away whole villages with
as much certainty as a fire or an inundation; and ships even have
been destroyed by these indefatigable republics. Our own docks and
embankments have been threatened by such minute ravagers.
The enormous injuries which insects cause to man may thus be held
as one reason for ceasing to consider the study of them as an
insignificant pursuit; for a knowledge of their structure, their food,
their enemies, and their general habits, may lead, as it often has
led, to the means of guarding against their injuries. At the same
time we derive from them both direct and indirect benefits. The honey
of the bee, the dye of the cochineal, and the web of the silk-worm,
the advantages of which are obvious, may well be balanced against
the destructive propensities of insects which are offensive to man.
But a philosophical study of natural history will teach us that the
direct benefits which insects confer upon us are even less important
than their general uses in maintaining the economy of the world. The
mischiefs which result to us from the rapid increase and the activity
of insects are merely results of the very principle by which they
confer upon us numberless indirect advantages. Forests are swept
away by minute beetles; but the same agencies relieve us from that
extreme abundance of vegetable matter which would render the earth
uninhabitable were this excess not periodically destroyed. In hot
countries the great business of removing corrupt animal matter, which
the vulture and hyæna imperfectly perform, is effected with certainty
and speed by the myriads of insects that spring from the eggs deposited
in every carcase by some fly seeking therein the means of life for
her progeny. Destruction and reproduction, the great laws of nature,
are carried on very greatly through the instrumentality of insects;
and the same principle regulates even the increase of particular
species of insects themselves. When aphides are so abundant that we
know not how to escape their ravages, flocks of lady-birds instantly
cover our fields and gardens to destroy them. Such considerations as
these are thrown out to show that the subject of insects has a great
philosophical importance--and what portion of the works of nature has
not? The habits of all God's creatures, whether they are noxious, or
harmless, or beneficial, are worthy objects of our study. If they
affect ourselves, in our health or our possessions, whether for good
or for evil, an additional impulse is naturally given to our desire
to attain a knowledge of their properties. Such studies form one of
the most interesting occupations which can engage a rational and
inquisitive mind; and, perhaps, none of the employments of human life
are more dignified than the investigation and survey of the workings
and the ways of nature in the minutest of her productions.
The exercise of that habit of observation which can alone make a
naturalist--"an out-of-door naturalist," as Daines Barrington calls
himself--is well calculated to strengthen even the most practical and
merely useful powers of the mind. One of the most valuable mental
acquirements is the power of discriminating among things which differ
in many minute points, but whose general similarity of appearance
usually deceives the common observer into a belief of their identity.
The study of insects, in this point of view, is most peculiarly adapted
for youth. According to our experience, it is exceedingly difficult for
persons arrived at manhood to acquire this power of discrimination;
but, in early life, a little care on the part of the parent or teacher
will render it comparatively easy. In this study the knowledge of
things should go along with that of words. "If names perish," says
Linnæus, "the knowledge of things perishes also:"[J] and, without
names, how can any one communicate to another the knowledge he has
acquired relative to any particular fact, either of physiology, habit,
utility, or locality? On the other hand, mere catalogue learning is as
much to be rejected as the loose generalizations of the despisers of
classification and nomenclature. To name a plant, or an insect, or a
bird, or a quadruped rightly, is one step towards an accurate knowledge
of it; but it is not the knowledge itself. It is the means, and not the
end in natural history, as in every other science.
If the bias of opening curiosity be properly directed, there is not
any branch of natural history so fascinating to youth as the study of
insects. It is, indeed, a common practice in many families to teach
children, from their earliest infancy, to treat the greater number
of insects as if they were venomous and dangerous, and, of course,
meriting to be destroyed, or at least avoided with horror. Associations
are by this means linked with the very appearance of insects, which
become gradually more inveterate with advancing years; provided, as
most frequently happens, the same system be persisted in, of avoiding
or destroying almost every insect which is unlucky enough to attract
observation. How much rational amusement and innocent pleasure is
thus thoughtlessly lost; and how many disagreeable feelings are thus
created, in the most absurd manner! In order to show that the study
or (if the word be disliked) the observation of insects is peculiarly
fascinating to children, even in their early infancy, we may refer
to what we have seen in the family of a friend, who is partial to
this, as well as to all the departments of natural history. Our
friend's children, a boy and girl, were taught, from the moment they
could distinguish insects, to treat them as objects of interest and
curiosity, and not to be afraid even of those which wore the most
repulsive appearance. The little girl, for example, when just beginning
to walk alone, encountered one day a large staphylinus (_Goërius
olens?_ Stephens; vulgo, _the devil's coach-horse_), which she
fearlessly seized, and did not quit her hold, though the insect grasped
one of her fingers in his formidable jaws. The mother, who was by,
knew enough of the insect to be rather alarmed for the consequences,
though she prudently concealed her feelings from the child. She did
well; for the insect was not strong enough to break the skin, and
the child took no notice of its attempts to bite her finger. A whole
series of disagreeable associations with this formidable-looking family
of insects was thus averted at the very moment when a different mode
of acting on the part of the mother would have produced the contrary
effect. For more than two years after this occurrence the little girl
and her brother assisted in adding numerous specimens to their father's
collection, without the parents ever having cause, from any accident,
to repent of their employing themselves in this manner. The sequel
of the little girl's history strikingly illustrates the position for
which we contend. The child happened to be sent to a relative in the
country, where she was not long in having carefully instilled into her
mind all the usual antipathies against "everything that creepeth on
the earth;" and though she afterwards returned to her paternal home,
no persuasion or remonstrance could ever again persuade her to touch
a common beetle, much less a staphylinus, with its tail turned up in
a threatening attitude, and its formidable jaws ready extended for
attack or defence.[K] We do not wish that children should be encouraged
to expose themselves to danger in their encounters with insects. They
should be taught to avoid those few which are really noxious--to admire
all--to injure none.
The various beauty of insects--their glittering colours, their
graceful forms--supplies an inexhaustible source of attraction. Even
the most formidable insects, both in appearance and reality,--the
dragon-fly, which is perfectly harmless to man, and the wasp, whose
sting every human being almost instinctively shuns,--are splendid in
their appearance, and are painted with all the brilliancy of natural
hues. It has been remarked that the plumage of tropical birds is not
superior in vivid colouring to what may be observed in the greater
number of butterflies and moths.[L] "See," exclaims Linnæus, "the
large, elegant painted wings of the butterfly, four in number, covered
with delicate feathery scales! With these it sustains itself in the
air a whole day, rivalling the flight of birds and the brilliancy
of the peacock. Consider this insect through the wonderful progress
of its life,--how different is the first period of its being from
the second, and both from the parent insect! Its changes are an
inexplicable enigma to us: we see a green caterpillar, furnished with
sixteen feet, feeding upon the leaves of a plant; this is changed into
a chrysalis, smooth, of golden lustre, hanging suspended to a fixed
point, without feet, and subsisting without food; this insect again
undergoes another transformation, acquires wings, and six feet, and
becomes a gay butterfly, sporting in the air, and living by suction
upon the honey of plants. What has nature produced more worthy of
our admiration than such an animal, coming upon the stage of the
world, and playing its part there under so many different masks?" The
ancients were so struck with the transformations of the butterfly,
and its revival from a seeming temporary death, as to have considered
it an emblem of the soul, the Greek word _pysche_ signifying both the
soul and a butterfly; and it is for this reason that we find the
butterfly introduced into their allegorical sculptures as an emblem
of immortality. Trifling, therefore, and perhaps contemptible, as to
the unthinking may seem the study of a butterfly, yet when we consider
the art and mechanism displayed in so minute a structure,--the fluids
circulating in vessels so small as almost to escape the sight--the
beauty of the wings and covering--and the manner in which each part
is adapted for its peculiar functions,--we cannot but be struck with
wonder and admiration, and allow, with Paley, that "the production of
beauty was as much in the Creator's mind in painting a butterfly as in
giving symmetry to the human form."
A collection of insects is to the true naturalist what a collection
of medals is to the accurate student of history. The mere collector,
who looks only to the shining wings of the one, or the green rust of
the other, derives little knowledge from his pursuit. But the cabinet
of the naturalist becomes rich in the most interesting subjects of
contemplation, when he regards it in the genuine spirit of scientific
inquiry. What, for instance, can be so delightful as to examine the
wonderful variety of structure in this portion of the creation; and,
above all, to trace the beautiful gradations by which one species runs
into another? Their differences are so minute, that an unpractised
eye would proclaim their identity; and yet, when the species are
separated, and not very distantly, they become visible even to
the common observer. It is in examinations such as these that the
naturalist finds a delight of the highest order. While it is thus one
of the legitimate objects of his study to attend to minute differences
of structure, form, and colouring, he is not less interested in the
investigation of habits and economy; and in this respect the insect
world is inexhaustibly rich. We find herein examples of instinct to
parallel those of all the larger animals, whether they are solitary
or social; and innumerable others besides, altogether unlike those
manifested in the superior departments of animated nature. These
instincts have various directions, and are developed in a more or less
striking manner to our senses, according to the force of the motive by
which they are governed. Some of their instincts have for their object
the preservation of insects from external attack; some have reference
to procuring food, and involve many remarkable stratagems; some direct
their social economy, and regulate the condition under which they
live together either in monarchies or republics, their colonizations,
and their migrations; but the most powerful instinct which belongs
to insects has regard to the preservation of their species. We find,
accordingly, that as the necessity for this preservation is of the
utmost importance in the economy of nature, so for this especial object
many insects, whose offspring, whether in the egg or the larva state,
are peculiarly exposed to danger, are endued with an almost miraculous
foresight, and with an ingenuity, perseverance, and unconquerable
industry, for the purpose of avoiding those dangers, which are not to
be paralleled even by the most singular efforts of human contrivance.
The same ingenuity which is employed for protecting either eggs, or
caterpillars and grubs, or pupæ and chrysalides, is also exercised
by many insects for their own preservation against the changes of
temperature to which they are exposed, or against their natural
enemies. Many species employ those contrivances during the period of
their hibernation, or winter sleep. For all these purposes some dig
holes in the earth, and form them into cells; others build nests of
extraneous substances, such as bits of wood and leaves; others roll
up leaves into cases, which they close with the most curious art;
others build a house of mud, and line it with the cotton of trees, or
the petals of the most delicate flowers; others construct cells, of
secretions from their own bodies; others form cocoons, in which they
undergo their transformation; and others dig subterraneous galleries,
which, in their complexity of arrangement, in solidity, and in complete
adaptation to their purposes, vie with the cities of civilised man. The
contrivances by which insects effect these objects have been accurately
observed and minutely described, by patient and philosophical
inquirers, who knew that such employments of the instinct with which
each species is endowed by its Creator offered the most valuable and
instructive lessons, and opened to them a wide field of the most
delightful study. The construction of their habitations is certainly
among the most remarkable peculiarities in the economy of insects; and
it is of this subject that we propose to treat under the general name,
which is sufficiently applicable to our purpose, of Insect Architecture.
In the descriptions which we shall give of Insect Architecture, we
shall employ as few technical words as possible: and such as we cannot
well avoid, we shall explain in their places; but, since our subject
chiefly relates to the reproduction of insects, it may be useful to
many readers to introduce here a brief description of the changes which
they undergo.
[Illustration: Magnified eggs, of _a_, _Geometra armillata_; _b_, of an
unknown water insect; _c_, of the lacquey moth; _d_, of a caddis-fly
(_Phryganea atrata_); _e_, of red under-wing moth (_Catocala nupta_);
_f_, of _Pontia Brassicæ_; _g_, of the Clifden Nonpareil moth.]
It was of old believed that insects were produced spontaneously by
putrefying substances; and Virgil gives the details of a process for
_creating_ a swarm of bees out of the carcase of a bull; but Redi, a
celebrated Italian naturalist, proved by rigid experiments that they
are always, in such cases, hatched from _eggs_ previously laid. Most
insects, indeed, lay eggs, though some few are viviparous, and some
propagate both ways. The eggs of insects are very various in form,
and seldom shaped like those of birds. We have here figured those of
several species, as they appear under the microscope.
When an insect first issues from the egg, it is called by naturalists
_larva_, and, popularly, a caterpillar, a grub, or a maggot. The
distinction, in popular language, seems to be, that _caterpillars_ are
produced from the eggs of moths or butterflies; _grubs_ from the eggs
of beetles, bees, wasps, &c.; and _maggots_ (which are without feet)
from blow-flies, house-flies, cheese-flies, &c., though this is not
very rigidly adhered to in common parlance. Maggots are also sometimes
called _worms_, as in the instance of the meal-worm; but the common
earth-worm is not a larva, nor is it by modern naturalists ranked among
insects.
[Illustration: _a_, Ametabolous pupa of Cicada; _b_, caterpillar of
tussock moth (_Laria fascelina_); _c_, larva of the poplar beetle
(_Chrysomela populi_); _d_, larva of Sinex; _e_, larva of the common
gnat.]
There are, however, certain larvæ, as those of the Cicada, the
crickets, the water-boatman (_Notonecta_), the cockroach, &c., which
resemble the perfect insects in form, excepting that they are destitute
of wings; but in the pupa state these appear in a rudimentary
condition, at least in such species as have wings in the mature stage
of existence. The pupæ are active and eat. Insects, the larvæ and pupæ
of which are so similar to the adults, are termed _Ametabolous_ (_a_,
without, [Greek: metabolê], change); those the larvæ of which undergo
changes of a marked character, _Metabolous_ (_Insecta ametabola_ and
_Insecta metabola_, Burmeister).
Larvæ are remarkably small at first, but grow rapidly. The full-grown
caterpillar of the goat-moth (_Cossus ligniperda_) is thus seventy-two
thousand times heavier than when it issues from the egg; and the
maggot of the blow-fly is, in twenty-four hours, one hundred and
fifty-five times heavier than at its birth. Some larvæ have feet,
others are without; none have wings. They cannot propagate. They feed
voraciously on coarse substances; and as they increase in size, which
they do very rapidly, they cast their skins three or four times. In
defending themselves from injury, and in preparing for their change by
the construction of secure abodes, they manifest great ingenuity and
mechanical skill. The figures on the preceding page exemplify various
forms of insects in this stage of their existence.
[Illustration: _a_, Pupa of a Water-Beetle (_Hydrophilus_); _b_, pupa
of _Sphinx Ligustri_.]
When larvæ are full grown, they cast their skins for the last time,
undergo a complete change of form, excepting in the case of ametabolous
larvæ, cease to eat, and remain nearly motionless. The inner skin
of the larva now becomes converted into a membranous or leathery
covering, which wraps the insect closely up like a mummy: in this
condition it is termed _Pupa_, from its resemblance to an infant in
swaddling bands. Nympha, or nymph, is another term given to insects
in this stage;[M] moreover from the pupæ of many of the butterflies
appearing gilt as if with gold, the Greeks called them _Chrysalides_,
and the Romans _Aureliæ_, and hence naturalists frequently call a pupa
_chrysalis_, even when it is not gilt. We shall see, as we proceed,
the curious contrivances resorted to for protecting insects in this
helpless state. The following are examples of insects in the _imago_,
or perfect state.
[Illustration: Insects in the Imago or perfect state.
_a_, _Nemopteryx coa_, Leach.--_b_, _Myrmeleon formicalynx_,
Fabricius.--_c_, _Hesperia comma_, Fabricius.--_d_, _Nepa cinerea_,
Linnæus.]
After a certain time, the insect which has remained in its pupa-case,
like a mass of jelly without shape, is gradually preparing for its
final change, when it takes the form of a perfect insect. This state
was called by Linnæus _Imago_, because the insect, having thrown off
its mask, becomes a perfect _image_ of its species. Of some, this
last portion of their existence is very short, others live through
a year, and some exist for longer periods. They feed lightly, and
never increase in size. The chief object of all is to perpetuate
their species, after which the greater number quickly die. It is in
this state that they exercise those remarkable instincts for the
preservation of their race, which are exhibited in their preparations
for the shelter of their eggs, and the nourishment of their larvæ.
_CHAPTER II._
STRUCTURES FOR PROTECTING EGGS.--MASON-WASPS; MASON-BEES; MINING-BEES.
The provisions which are made by the different species of insects
for protecting their eggs, appear in many cases to be admirably
proportioned to the kind of danger and destruction to which they
may be exposed. The eggs themselves, indeed, are not so liable to
depredation and injury as the young brood hatched from them; for, like
the seeds of plants, they are capable of withstanding greater degrees
both of heat and cold than the insects which produce them. According
to the experiments of Spallanzani, the eggs of frogs that had been
exposed to various degrees of artificial heat were scarcely altered in
their productive powers by a temperature of 111° of Fahrenheit, but
they became corrupted after 133°. He tried the same experiment upon
tadpoles and frogs, and found they all died at 111°. Silkworms died at
a temperature of 108°, while their eggs did not entirely cease to be
fertile till 144°. The larvæ of flesh-flies perished, while the eggs
of the same species continued fertile, at about the same comparative
degrees of heat as in the preceding instances. Intense cold has a
still less effect upon eggs than extreme heat. Spallanzani exposed the
eggs of silk-worms to an artificial cold 23° below zero, and yet, in
the subsequent spring, they all produced caterpillars. Insects almost
invariably die at the temperature of 14°, that is, at 18° below the
freezing point.[N] The care of insects for the protection of their eggs
is not entirely directed to their preservation in the most favourable
temperature for being hatched, but to secure them against the numerous
enemies which would attempt their destruction; and, above all, to
protect the grubs, when they are first developed, from those injuries
to which they are peculiarly exposed. Their prospective contrivances
for accomplishing these objects are in the highest degree curious.
Most persons have more or less acquaintance with the hives of the
social species of bees and wasps; but little is generally known of the
nests constructed by the solitary species, though in many respects
these are not inferior to the others in displays of ingenuity and
skill. We admire the social bees, labouring together for one common
end, in the same way that we look with delight upon the great division
of labour in a well-ordered manufactory. As in a cotton-mill some
attend to the carding of the raw material, some to its formation into
single threads, some to the gathering these threads upon spindles,
others to the union of many threads into one,--all labouring with
invariable precision because they attend to a single object;--so do
we view with delight and wonder the successive steps by which the
hive-bees bring their beautiful work to its completion,--striving, by
individual efforts, to accomplish their general task, never impeding
each other by useless assistance, each taking a particular department,
and each knowing its own duties. We may, however, not the less admire
the solitary wasp or bee, who begins and finishes every part of its
destined work; just as we admire the ingenious mechanic who perfects
something useful or ornamental entirely by the labour of his own
hands,--whether he be the patient Chinese carver, who cuts the most
elaborately-decorated boxes out of a solid piece of ivory, or the
turner of Europe, who produces every variety of elegant form by the
skilful application of the simplest means.
Our island abounds with many varieties of solitary wasps and bees; and
their nests may therefore be easily discovered by those who, in the
proper seasons, are desirous of observing the peculiarities of their
architecture.
[Illustration: _Odynerus._--Natural size.]
Mason-Wasps.
In September, 1828, a common species of solitary mason-wasp
(_Odynerus_, Latr.) was observed by us (J. R.) on the east wall of
a house at Lee, in Kent, very busy in excavating a hole in one of
the bricks, about five feet from the ground. Whether there might not
have been an accidental hole in the brick before the wasp commenced
her labours, is unknown, as she had made considerable progress in
the work when first observed: but the brick was one of the hardest
of the yellow sort made in this neighbourhood. The most remarkable
circumstance in the process of hewing into the brick was the care of
the insect in removing to a distance the fragments which from time
to time she succeeded in detaching. It did not appear to suit her
design to wear down the brick, particle by particle, as the furniture
beetle (_Anobium pertinax_) does in making its pin-hole galleries in
old wood. Our wasp-architect, on the contrary, by means of her strong
_tranchant_-toothed jaws, severed a piece usually about the bigness
of a mustard-seed. It might have been supposed that these fragments
would have been tossed out of the hole as the work proceeded, without
further concern; as the mole tosses above ground the earth which
has been cleared out of its subterranean gallery. The wasp was of a
different opinion; for it was possible that a heap of brick chips,
at the bottom of the wall, might lead to the discovery of her nest
by some of her enemies, particularly by one or other of the numerous
tribe of what are called _ichneumon_-flies. This name is given to
them, from the similarity of their habit of destroying eggs, to that
of the little animal which proves so formidable an enemy to the
multiplication of the crocodile of Egypt. They may be also denominated
_cuckoo_-flies, because, like that bird, they thrust their egg into
the nest of another species. These flies are continually prowling
about and prying into every corner, to find, by stealth, a nidus for
their eggs. It might have been some such consideration as this which
induced the wasp to carry off the fragments as they were successively
detached. That concealment was the motive, indeed, was proved: for
one of the fragments which fell out of the hole by accident, she
immediately sought for at the bottom of the wall, and carried off
like the rest. It was no easy matter to get out one of the fragments,
as may readily be conceived when the size of the insect is compared
with that of the entrance of which this ([Illustration]) is the exact
size, as taken from the impression of a bit of dough upon the hole
when finished. It was only by seizing the fragment with her jaws, and
retreating backwards, that the matter could be accomplished; though,
after the interior of the excavation was barely large enough to admit
of her turning round, she more than once attempted to make her exit
head-foremost, but always unsuccessfully. The weight of the fragments
removed did not appear to impede her flight, and she generally returned
to her task in about two or three minutes.
[Illustration: Mandibles--Jaws of Mason-Wasp.--Greatly magnified.]
Within two days the excavation was completed; but it required two other
days to line it with a coating of clay, to deposit the eggs, two in
number, and, no doubt, to imprison a few live spiders or caterpillars
for the young when hatched--a process which was first observed by Ray
and Willughby,[O] but which has since been frequently ascertained. In
the present instance, this peculiarity was not seen; but the little
architect was detected in closing up the entrance, which was formed of
a layer of clay more than double the thickness of the interior lining.
In November following, we hewed away the brick around this nest, and
found the whole excavation was rather less than an inch in depth.
[Illustration: Cuckoo-Fly (_Tachina larvarum?_).--Natural size.]
Notwithstanding all the precautions of the careful parent to conceal
her nest it was found out by one of the cuckoo-flies (_Tachina
larvarum?_)--probably a common species very similar to the house-fly,
but rather larger, which deposited an egg there; and the grub hatched
from it, after devouring one of the wasp-grubs, formed itself a cocoon
(_a_), as did the other undevoured grub of the wasp (_b_). Both awaited
the return of summer to change into winged insects, burst their
cerements, and proceed as their parents did.
[Illustration: Mason-Wasp's Nest and Cocoons.--About one-third the
natural size.]
[Illustration: Mason-Wasp (_Odynerus murarius_).--Natural size.]
Another mason-wasp (_Odynerus murarius_, Latr.), differing little in
appearance from the former, may often be seen frequenting sandy banks
exposed to the sun, and constructing its singular burrows. The sort
of sand-bank which it selects is hard and compact; and though this
may be more difficult to penetrate, the walls are not liable to fall
down upon the little miner. In such a bank, the mason-wasp bores a
tubular gallery two or three inches deep. The sand upon which Réaumur
found some of these wasps at work was almost as hard as stone, and
yielded with difficulty to his nail; but the wasps dug into it with
ease, having recourse, as he ascertained, to the ingenious device of
moistening it by letting fall two or three drops of fluid from their
mouth, which rendered the mass ductile, and the separation of the
grains easy to the double pickaxe of the little pioneers.
[Illustration: Nests, &c., of Mason-Wasps.--About half the natural size.
_a_, The tower of the nest; _b_, the entrance after the tower is
removed; _c_, the cell; _d_, the cell, with a roll of caterpillars
prepared for the larva.]
When this wasp has detached a few grains of the moistened sand, it
kneads them together into a pellet about the size of one of the seeds
of a gooseberry. With the first pellet which it detaches, it lays
the foundation of a round tower, as an outwork, immediately over the
mouth of its nest. Every pellet which it afterwards carries off from
the interior is added to the wall of this outer round tower, which
advances in height as the hole in the sand increases in depth. Every
two or three minutes, however, during these operations, it takes a
short excursion, for the purpose, probably, of replenishing its store
of fluid wherewith to moisten the sand. Yet so little time is lost,
that Réaumur has seen a mason-wasp dig in an hour a hole the length of
its body, and at the same time build as much of its round tower. For
the greater part of its height this round tower is perpendicular; but
towards the summit it bends into a curve, corresponding to the bend
of the insect's body, which in all cases of insect architecture, is
the model followed. The pellets which form the walls of the tower are
not very nicely joined, and numerous vacuities are left between them,
giving it the appearance of filigree-work. That it should be thus
slightly built is not surprising, for it is intended as a temporary
structure for protecting the insect while it is excavating its hole,
and as a pile of materials, well arranged and ready at hand, for the
completion of the interior building,--in the same way that workmen make
a regular pile of bricks near the spot where they are going to build.
This seems, in fact, to be the main design of the tower, which is taken
down as expeditiously as it had been reared. Réaumur thinks that, by
piling in the sand which has previously been dug out, the wasp intends
to guard her progeny for a time from being exposed to the too violent
heat of the sun; and he has even sometimes seen that there were not
sufficient materials in the tower, in which case the wasp had recourse
to the rubbish she had thrown out after the tower was completed. By
raising a tower of the materials which she excavates, the wasp produces
the same shelter from external heat as a human creature would who chose
to inhabit a deep cellar of a high house. She further protects her
progeny from the ichneumon-fly, as the engineer constructs an outwork
to render more difficult the approach of an enemy to the citadel.
Réaumur has seen this indefatigable enemy of the wasp peep into the
mouth of the tower, and then retreat, apparently frightened at the
depth of the cell which he was anxious to invade.
The mason-wasp does not furnish the cell she has thus constructed with
pollen and honey, like the solitary bees, but with living caterpillars,
and these always of the same species--being of a green colour, and
without feet. She fixes the caterpillars together in a spiral column:
they cannot alter their position, although they remain alive. They
are an easy prey to their smaller enemy; and when the grub has eaten
them all up, it spins a case, and is transformed into a pupa, which
afterwards becomes a wasp. The number of caterpillars which is thus
found in the lower cavity of the mason-wasp's nest is ordinarily from
ten to twelve. The mother is careful to lay in the exact quantity of
provision which is necessary to the growth of the grub before he quits
his retreat. He works through his store till his increase in this
state is perfected, and he is on the point of undergoing a change into
another state, in which he requires no food. The careful purveyor,
cruel indeed in her choice of a supply, but not the less directed by
an unerring instinct, selects such caterpillars as she is conscious
have completed their growth, and will remain thus imprisoned without
increase or corruption till their destroyer has gradually satisfied
the necessities of his being. "All that the worm of the wasp," says
Réaumur, "has to do in his nest, from his birth to his transformation,
is to eat." There is another species of wasp which does not at once
enclose in its nest all the sustenance which its larva will require
before transformation, but which from time to time imprisons a living
caterpillar, and when that is consumed, opens the nest and introduces
another.
[The upper figure in the accompanying illustration exhibits two of the
curious towers built by this interesting insect and drawn of their
natural size.]
The insect is one of the most plentiful in England, and can be found
on sunny days, flitting about sand-banks and making its curious
habitations. The length is nearly half an inch, and the colour is
black, variegated with five yellow bands upon the abdomen.
The lower figure represents the habitations of one of the British
solitary wasps, _Pompilus punctum_, and is given in order to show a
curious resemblance in the structure. The specimen from which the
sketch was taken was found under the eaves of a roof which protected
a bee-hive. The cells were thirteen in number, very carefully
constructed of earth, and several of them were closed. Although these
cells were not fossorial in their nature, several other species of
the same genus are as accomplished burrowers as any insect. _Pompilus
plumbeus_, for example, another black species, burrows into sand, and
is very plentiful on our more southern shores. It may usually be found
hovering about sand-banks, and flitting about with such agility that it
is by no means an easy insect to catch. The male is peculiarly apt to
evade the stroke of the entomologist's net.
[Illustration]
[Illustration]
Then there is _Pompilus rufipes_, which is a black insect, but
distinguished by the conspicuous red colour of the hind legs. This is
very fond of our coasts, and may be found wherever the soil is suitable
for its excavations. Many species of this genus carry off spiders for
the purpose of provisioning their nests. Several species, which live
far inland, prefer light and dry earth to sand, and make therein their
burrows, preferring our little white spider as the provision for their
young. Although the same insect may be often observed to carry the
same kind of prey to its home, it does not at all follow that no change
is ever made.
But the most remarkable example of this fact may be found in a very
common swift-winged insect, black in colour, with a reddish patch on
the end of the abdomen. Its name is _Trachytes pompiliformis_, and
it generally stocks its nest with small caterpillars. Mr. F. Smith,
however, has taken it when in the act of carrying off a small species
of grasshopper--certainly the very last insect that would be thought of
as likely to be immured by a captor which must be scarcely larger than
itself.
This insect is to be found in most warm and sandy situations, and may
be looked for at the end of summer and beginning of autumn. It may be
easily known by its red spot on the abdomen, and the large, transverse
head; it is wider than the thorax.
One species of mining-bee, not often found in England, chooses some
very singular insects wherewith to feed its young. Its name is
_Philanthus triangulum_, and it is a very fierce, waspish-looking
creature, with a large wide head, wider even than the thorax, sharp and
powerful jaws, and with broad wings. The head and thighs are black,
with a few spots of a yellowish white, and the abdomen is yellow, with
a black spot in the middle of each segment. Its length rather exceeds
half an inch. The actions of this insect do not belie its looks, for it
is a fierce and active creature, seizing upon various bees and dragging
them into its tunnel.
Mr. F. Smith discovered the metropolis of this usually scarce insect
at Sandown Bay, in the Isle of Wight, and has given an interesting
description of its habits. He states that although it is so ferocious
towards other insects, it appears to be perfectly harmless as far as
man is concerned, allowing itself to be handled without even attempting
to use its sting. Indeed, he was quite unable to provoke the insect to
do so. Various bees were captured by the Philanthus, and the favourites
seemed to belong to the genus Andrena, itself a burrowing bee, and the
common hive-bee. The Philanthus seemed perfectly indifferent whether
they attacked the comparatively small and feeble Andrena, or the
formidable hive-bee, taking them as they came, and caring nothing
for the sting. The Philanthus that burrowed on the top of the cliff,
seemed to prefer the hive-bee, because the red clover attracted greater
numbers of that insect. Those that made their burrows at the top of the
cliff, took the Andrenæ. Of course, the Philanthus is obliged to catch
more of the Andrenæ than the hive bees. Only one species of this genus
is known in England; it is to be found in July and August.
There is a very large genus of rather small humming-bees, many of which
are popularly mistaken for wasps, on account of their sharply pointed
and yellow banded abdomen; they belong to the genus Crabro, and are
extremely variable in the material into which they burrow, and the
insects with which they feed their young. Some species burrow into dry
bramble sticks. If the reader should wish to obtain specimens of them,
as well as other burrowers, he will find bramble, rose, and jessamine
sticks most prolific in them. The best plan is to collect a quantity
of these sticks and put them into glass tubes, with the ends stopped
with wire gauze; there is then an absolute certainty of identifying the
insect with its habitation. The spring is the best time for collecting.
Sometimes these creatures are afflicted with parasites, which also are
detained in the tube, so as to yield valuable information to the captor.
Some species burrow in sand-banks and feed their young with gnats,
others burrow into dead timber, and stock their tunnels with flies
of various kinds. One very useful species, _Crabro lævis_, burrows
in sand-banks, and provisions its nest with the noxious turnip-fleas
(_Halticæ_), great numbers of which are needed to stock a single
burrow. It is rather a social insect, many burrows being often found
near each other. The turnip-flea has so hard a shell, that the young
Crabro seems hardly capable of eating it. Mr. Smith, however, has
remarked that another burrowing-bee stocks its nest with certain
weevils that are almost too hard to be pierced with a pin, and that the
shell is probably softened by the damp ground. The greater number of
this group, however, are burrowers into the ground, and stock their
nests with flies of some kind.
Another species of this large genus, _Crabro luteipalpis_, is fond of
making its burrows in the mortar of old walls, preferring those spots
where nails have been drawn, making the process of burrowing easier
for the insect. It is not uncommon in the outskirts of London. All
gardeners, especially those who cultivate roses, ought to encourage
this very little insect, and welcome its presence, for it provisions
its nest with the aphides, or green blight, which infect the
rose-trees, and which have destroyed so many promising plants.
The female, which is the larger of the two sexes, measures only three
lines in length. The colour is shining black, and the head is rather
squared.
Among other burrowing species of this genus we may mention _Crabro
varius_, a rather long and slender insect, black in colour, with yellow
spottings about the thorax. It prefers very hard fine sand, such as is
found in partially excavated sand-banks, and provisions its burrows
with gnats. It is tolerably plentiful.
Our last example of the earth-burrowers belonging to this genus is
_Crabro Wesmoeli_, which chooses similar localities, being mostly found
in sand-banks. It carries off flies of different kinds for the food
of its young. There is a very common insect, closely allied to the
last mentioned genus, whose horns are worthy of notice. This is called
_Typoxylon figulus_. It is a small creature, with a large head and
slender abdomen. Its colour is black, and on the edges of the segments
of the abdomen there is a little silvery shining down.
It generally burrows into light earth, though it sometimes drives its
tunnel into decayed wood. In either case, it provisions its nest with
spiders, flying into the hedges, pulling the unfortunate spiders out
of their webs, and carrying them into the burrow. One burrow contains
a series of cells, which are separated from each other by partitions
of sand, the particles of which are firmly cemented together by some
glutinous substance secreted by the insect. Some species of this genus
burrow into the pith of the bramble and other shrubs.
One of the most determined of our British burrowers is the insect which
is known by the name of _Ammophila sabulosa_. It has a large, squared
head, wider than the thorax, a very long and slender body, and short
though powerful wings. The colour is black, with a slight rust-red tint
on the base of the abdomen.
When the female has dug her burrow, she sets off in search of a
caterpillar of proportionate size, and having conveyed it into her
dwelling, she affixes an egg to the imprisoned larva, and goes off in
search of another, carefully stopping up the entrance with stones. In
fine weather she will fill one burrow with caterpillars in a few hours,
and then begin another nursery for the future young. This species
appears always to make use of caterpillars, but another allied species
prefers spiders. Mr. F. Smith mentions that he has found in a high
sand-bank as many as twenty females apparently hibernating together
till suitable weather enabled them to pursue their usual economy.
There really seems to be scarcely any genus of insect that is not
seized upon by one or other of these burrowers, and packed away in a
half living state to form food for their young. There is one of these
solitary burrowing wasps called the _Astata boops_, deriving its
specific name from its large round eyes, which in the male completely
unite at the back of the head. The abdomen is shaped something like
a boy's peg-top, or a symmetrical turnip, the peg of the top, or the
point of the turnip, corresponding to the top of the abdomen. Its
length is about half an inch, and its colour is black, with a rust-red
patch on the end of the abdomen.
There is a remarkably pretty, and very variable, sand-wasp, which is
plentiful in most parts of the country. The colour is black, and the
abdomen is banded by four yellow bars. Its feet are also yellow. Mr.
Smith has written a very interesting account of the proceedings of this
insect.
"Having frequently observed the habits of the type of this genus,
_Mellinus arvensis_, and reared it from the larva state, a few
observations are here recorded. When the parent insect has formed
a burrow of the required length, and enlarged the extremity into
a chamber of proper dimensions, she issues forth in search of the
proper nutriment for her young; this consists of various dipterous
insects: species of various genera are equally adapted to her
purpose--_Muscidæ_, _Syrphidæ_, &c., are captured.
"It is amusing to see four or five females lie in wait upon a patch
of cow-dung until some luckless fly settles on it. When this happens,
a cunning and gradual approach is made; a sudden attempt would not
succeed. The fly is the insect of quickest flight, therefore a degree
of intrigue is necessary. This is managed by running past the victim
slowly, and apparently in an unconcerned manner, until the poor fly is
caught unawares, and carried off by the Mellinus to its burrow. The
first fly being deposited, an egg is laid. The necessary number of
flies are soon secured, and her task is completed. Sometimes she is
interrupted by rainy weather, and it is some days ere she can store up
the quantity required.
"A larva found feeding became full-fed in ten days. Six flies were
devoured, the heads, harder parts of the throat, portions of the
abdomen, and the legs, being left untouched. The larva spins a tough,
thin, brown silken cocoon, passes the winter and spring in the larva
state, changes to the nymph on the approach of summer, and appears
about the beginning of autumn in the perfect state."
There is a genus of hymenopterous insects known by the name of
_Scolia_, which are remarkable for their fossorial powers. The species
represented in the engraving is called _Scolia Xantiana_, and is a
native of California.
When the female Scolia is about to fulfil the great object for which
she came into the world, she looks about for a suitable spot, where
the ground is not too hard, and digs a perpendicular burrow of some
depth, enlarging it at the bottom, and digging horizontally, so that
the general shape of the burrow somewhat resembles that of a boot. When
the burrow is completed, the insect flies off in search of food for
its young, and presently returns, bearing with her a grub, which she
clasps tightly under her chest, so that her wings may be at liberty.
She then takes the grub to the bottom of the tunnel, deposits an egg
upon it, and if the grub be a small one, goes off to fetch another.
When a sufficiency of food has been obtained, she covers up the grub
and egg and leaves the latter to its fate. In due time it is hatched,
and begins straightway to feed upon its unfortunate fellow-prisoner.
When all the food is gone, it is old enough to assume the perfect form,
and when it finally becomes a perfect insect, it makes its way into the
open air, and straightway looks out for a mate.
[Illustration]
An European species of this genus, which is called _Scolia flavifrons_,
is remarkable for the four large, round spots on the upper surface
of the abdomen. This species always feeds its young on the grub of a
beetle, one of the lamellicorn group, and in this case the grub is so
large that one is sufficient.
In the illustration, the left hand figure shows a section of the burrow
of _Scolia Xantiana_, and exhibits the enlarged portion of the tunnel
in which are placed the young Scolia and the unfortunate grub which has
to serve it for food. The insect itself is seen in the centre.
For figures 3 and 4 the reader is referred to the heading "Spiders."
There is another British insect which feeds its young with flies, and
which catches them in a manner somewhat similar to that which has
recently been narrated when treating of the Mellinus. The insect in
question is called _Oxybelus unuglumis_, and is a very pretty species.
Its length is seldom much more than a quarter of an inch, and its
colour is black, with some silvery hair about the face, and with some
spots and bands of white, more or less yellowish, upon the pointed
abdomen. The male is usually smaller than the female, but compensates
for this want of size by his more brilliant colouring.
Mr. F. Smith has described to me the method employed by this insect in
catching flies. In the air it would not have a chance of success, and
so it proceeds after a fashion very much like that which is adopted
by the hunting-spider. Choosing some spot where flies are likely to
settle, such as a bare, sunny bank, the Oxybelus alights upon it and
begins to run about without any apparent motive. At first the flies
are rather alarmed, but after a while they become accustomed to the
rapid movements of their foe, and allow it to come nearer and nearer
the cause of its perambulations. As soon as it has succeeded in drawing
within a few inches of a fly, the Oxybelus leaps upon it, just like the
hunting spider on its prey, and flies off before the victim knows that
an attack is even meditated.
The burrow of this species is made in hard white sand.
Several species of the genus _Cerceris_ are noted, not only as
burrowers, but for the exceeding variety of the food which they store
in their dwellings. The most common species, _Cerceris arenaria_, makes
its tunnel in hard, sandy spots, and is usually to be found about the
middle of July and August. The length of this insect rather exceeds
half an inch, and its colour is black, profusely spotted and barred
with yellow. It is rather slenderly made, and gives little external
indications of the great strength which it possesses.
This insect prefers to stock its nest with weevils of different
kinds--a most singular choice, when the hardness of the exterior
is taken into consideration. The well-known nut-weevil (_Balaninus
nucum_), with its hard, round body, and long mouth, is frequently taken
by this species of Cerceris, and Mr. Smith further mentions that he
has captured it in the act of taking the weevil called _Otiorhynchus
sulcatus_ to its nest.
This beetle is among the most noxious of our garden foes, and the more
so because its ravages are unseen. In its larval state it infests the
roots of many of our succulent plants and flowers, and has a habit of
eating away the plant just at the junction of the root and stem. Even
flowers in pots are apt to be infested by this insect, and often die
without the cause of their death being discovered. It is about half an
inch in length, white, and is destitute of feet, their office being
performed by bundles of stiff hairs, which are dispersed round the body.
In its perfect state it is about the third of an inch in length, the
colour is black, covered with a coating of very fine and short grey
hairs, and along its back are a number of short longitudinal grooves.
From this latter circumstance it derives its name of "_sulcatus_," or
grooved.
The exterior of this beetle is extremely hard, even exceptionally so
among the hard-bodied weevils. It is extremely difficult to get a pin
through the body, and the entomologist is often obliged to bore a hole
with a stout needle before the pin can be inserted. Yet, the Cerceris
uses this insect as the food of its young, and stores them away in
its burrow. That the young should eat them seems as impossible as if
a lobster or a box-tortoise had been inserted in their place. It is,
however, thought by most practical entomologists that the shell of the
weevil is softened by lying in the damp ground, and that as the young
is not hatched for several days after the burrow is sealed up, the
hard wing cases have time to soften.
Another species of the same genus, _Cerceris interrupta_, has the
curious habit of making its burrow in the hardest ground which it can
penetrate, and is generally to be found in well used footpaths. This
species also uses weevils for the food of its young, but prefers those
small weevils which are classed under the genus _Apion_, and which are
readily known by their pear-shaped bodies and rather elongated heads.
[There are about seventy species of _Apion_, so that the Cerceris has
plenty of choice.]
Mason-Bees.
It would not be easy to find a more simple, and, at the same time,
ingenious specimen of insect architecture than the nests of those
species of solitary bees which have been justly called mason-bees
(_Megachile_, Latreille). Réaumur, who was struck by the analogies
between the proceedings of insects and human arts, first gave to bees,
wasps, and caterpillars those names which indicate the character of
their labours; and which, though they may be considered a little
fanciful, are at least calculated to arrest the attention. The nests
of mason-bees are constructed of various materials; some with sand,
some with earth mixed with chalk, and some with a mixture of earthy
substances and wood.
[Illustration: Mason-Bee (_Anthophora retusa_).--Natural size.]
On the north-east wall of Greenwich Park, facing the road, and about
four feet from the ground, we discovered (J. R.), December 10th, 1828,
the nest of a mason-bee, formed in the perpendicular line of cement
between two bricks. Externally there was an irregular cake of dry mud,
precisely as if a handful of wet road-stuff had been taken from a
cart-rut and thrown against the wall; though, upon closer inspection,
the cake contained more small stones than usually occur in the mud of
the adjacent cart-ruts. We should in fact have passed it by without
notice had there not been a circular hole on one side of it, indicating
the perforation of some insect. This hole was found to be the orifice
of a cell about an inch deep, exactly of the form and size of a lady's
thimble, finely polished, and of the colour of plaster-of-paris, but
stained in various places with yellow.
[Illustration: Exterior Wall of Mason-Bee's Nest.]
This cell was empty; but, upon removing the cake of mud, we discovered
another cell, separated from the former by a partition about a quarter
of an inch thick, and in it a living bee, from which the preceding
figure was drawn, and which, as we supposed, had just changed from the
pupa to the winged state, in consequence of the uncommon mildness of
the weather. The one which had occupied the adjacent cell had no doubt
already dug its way out of its prison, and would probably fall a victim
to the first frost.
[Illustration: Cells of a Mason-Bee (_Anthophora retusa_).--One-third
the natural size.]
Our nest contained only two cells--perhaps from there not being room
between the bricks for more.
[There are only four British species of this genus. One species, _A.
acervorum_, seems perfectly indifferent whether it burrows into banks
or into the mortar of old walls. If possible, the former locality seems
to be the most favoured.
This species is notable for the many parasites who infect the
habitation and destroy the inmates. Perhaps the very worst and most
destructive of these parasites is the common earwig, which wreaks
wholesale desolation in the nest. It creeps into the burrow, and if it
finds a store of pollen laid up for the young, it will eat the pollen.
But if the young grub be hatched it will eat the grub. If the inmate
be in the pupal state, or even if it be ready to emerge in its perfect
condition, the earwig will eat it.
There are two bees which are parasitic upon this unfortunate insect,
both belonging the genus _Melecta_.
But the most destructive of these parasites appears to be an insect
which belongs to the great family of _Chalcididæ_. These insects are
of the hymenopterous order, are of very minute dimensions, and of the
most brilliant colours. Indeed, if they were an inch or two in length,
instead of the eighth or twelfth of an inch, they would not suffer in
comparison with the most gorgeous inhabitants of tropical countries.
Their forms are most eccentric, some species having the abdomen small
and round and set on a long footstalk, while others have that portion
of the body placed so closely against the thorax, that the short
footstalk is scarcely visible. Others have certain joints of the legs
so large that a single joint equals the entire abdomen. Some have
the ovipositor projecting boldly from the body, while others have it
tucked up underneath, and others again have it quite short. But there
is one point which distinguishes them all, namely, the almost veinless
character of the wings.
Some of the _Chalcididæ_ are parasitic upon insects in their earliest
stages, actually depositing their eggs in those of moths and
butterflies. Others are entirely parasitic upon parasites, laying
their eggs in the aphidii, which are parasites of the aphis. Some
of them haunt the galls, and contrive to make their young parasitic
upon the immature cynipidæ which lie within the gall. The common
small tortoise-shell butterfly is terribly infested with these little
creatures, and we have bred hundreds of the gem-like _Chalcididæ_ from
the larvæ and pupæ of that butterfly.
One of the _Chalcididæ_, belonging to the genus _Melittobia_, is a
parasite upon the _Anthophora_; and the curious part of the proceeding
is, that it finds there another parasite, which becomes developed in
the home of the bee: the _Melittobia_ feeds indiscriminately upon the
bee and parasite.
Although the _Melittobia_ does not make such wholesale destruction as
is wrought by the earwig when it gets into a nest, it does more damage
to the bee, on account of its great numbers. Some three or four females
will lay a great quantity of eggs within a nest, and from those eggs a
hundred of the young will be developed. When the larvæ are fully grown,
they quit their hold of their prey, and fall to the bottom of the cell,
where they lie until they have assumed the perfect form. They then
burst forth, together with those of the bee that may have escaped their
attacks.]
An interesting account is given by Réaumur of another mason-bee
(_Megachile muraria_), not a native of Britain, selecting earthy sand,
grain by grain; her glueing a mass of these together with saliva, and
building with them her cells from the foundation. But the cells of
the Greenwich Park nest were apparently composed of the mortar of the
brick wall; though the external covering seems to have been constructed
as Réaumur describes his nest, with the occasional addition of small
stones.
About the middle of May, 1829, we discovered the mine from which all
the various species of mason-bees in the vicinity seemed to derive
materials for their nests. (J. R.) It was a bank of brown clay, facing
the east, and close by the margin of the river Ravensbourn, at Lee,
in Kent. The frequent resort of the bees to this spot attracted the
attention of some workmen, who, deceived by their resemblance to
wasps, pointed it out as a wasps' nest; though they were not a little
surprised to see so numerous a colony at this early season. As the
bees had dug a hole in the bank, where they were incessantly entering
and reappearing, we were of opinion that they were a peculiar sort of
the social earth-bees (_Bombi_). On approaching the spot, however, we
remarked that the bees were not alarmed, and manifested none of the
irritation usual in such cases, the consequence of jealous affection
for their young. This led us to observe their operations more minutely;
and we soon discovered that on issuing from the hole each bee carried
out in its mandibles a piece of clay. Still supposing that they
were social earth-bees, we concluded that they were busy excavating
a hollow for their nest, and carrying off the refuse to prevent
discovery. The mouth of the hole was overhung, and partly concealed,
by a large pebble. This we removed, and widened the entrance of the
hole, intending to dig down and ascertain the state of the operations;
but we soon found that it was of small depth. The bees, being scared
away, began scooping out clay from another hole about a yard distant
from the first. Upon our withdrawing a few feet from the first hole,
they returned thither in preference, and continued assiduously digging
and removing the clay. It became obvious, therefore, from their thus
changing place, that they were not constructing a nest, but merely
quarrying for clay as a building material. By catching one of the bees
(_Osmia bicornis_) when it was loaded with its burden, we ascertained
that the clay was not only carefully kneaded, but was also more moist
than the mass from which it had been taken. The bee, therefore, in
preparing the pellet, which was nearly as large as a garden-pea, had
moistened it with its saliva, or some similar fluid, to render it, we
may suppose, more tenacious, and better fitted for building. The reason
of their digging a hole, instead of taking clay indiscriminately from
the bank, appeared to be for the purpose of economizing their saliva,
as the weather was dry, and the clay at the surface was parched and
hard. It must have been this circumstance which induced them to prefer
digging a hole, as it were, in concert, though each of them had to
build a separate nest.
The distance to which they carried the clay was probably considerable,
as there was no wall near, in the direction they all flew towards, upon
which they could build; and in the same direction also, it is worthy
of remark, they could have procured much nearer the very same sort of
clay. Whatever might be the cause of their preference, we could not
but admire their extraordinary industry. It did not require more than
half a minute to knead one of the pellets of clay; and, from their
frequent returns, probably not more than five minutes to carry it to
the nest, and apply it where wanted. From the dryness of the weather,
indeed, it was indispensable for them to work rapidly, otherwise the
clay could not have been made to hold together. The extent of the whole
labour of forming a single nest may be imagined, if we estimate that
it must take several hundred pellets of clay for its completion. If a
bee work fourteen or fifteen hours a-day, therefore, carrying ten or
twelve pellets to its nest every hour, it will be able to finish the
structure in about two or three days; allowing some hours of extra time
for the more nice workmanship of the cells in which the eggs are to be
deposited, and the young grubs reared.
That the construction of such a nest is not a merely agreeable exercise
to the mason-bee has been sufficiently proved by M. Du Hamel. He has
observed a bee (_Megachile muraria_) less careful to perform the
necessary labour for the protection of her offspring than those we
have described, but not less desirous of obtaining this protection,
attempt to usurp the nest which another had formed. A fierce battle
was invariably the consequence of this attempt; for the true mistress
would never give place to the intruder. The motive for the injustice
and the resistance was an indisposition to further labour. The trial of
strength was probably, sometimes, of as little use in establishing the
right as it is amongst mankind; and the proper owner, exhausted by her
efforts, had doubtless often to surrender to the dishonest usurper.
The account which Réaumur has given of the operations of this class
of bees differs considerably from that which we have here detailed;
from the species being different, or from his bees not having been able
to procure moist clay. On the contrary, sand was the chief material
used by the mason-bees (_Megachile muraria_); which they had the
patience to select from the walks of a garden, and knead into a paste
or mortar, adapted to their building. They had consequently to expend
a much greater quantity of saliva than our bees (_Osmia bicornis_),
which worked with moist clay. Réaumur, indeed, ascertained that every
individual grain of sand is moistened previous to its being joined to
the pellet, in order to make it adhere more effectually. The tenacity
of the mass is, besides, rendered stronger, he tells us, by adding a
proportion of earth or garden-mould. In this manner, a ball of mortar
is formed, about the size of a small shot, and carried off to the nest.
When the structure of this is examined, it has all the appearance
externally of being composed of earth and small stones or gravel. The
ancients, who were by no means accurate naturalists, having observed
bees carrying pellets of earth and small stones, supposed that they
employed these to add to their weight, in order to steady their flight
when impeded by the wind.
The nests thus constructed appear to have been more durable edifices
than those which have fallen under our observation;--for Réaumur says
they were harder than many sorts of stone, and could scarcely be
penetrated with a knife. Ours, on the contrary, do not seem harder
than a piece of sun-baked clay, and by no means so hard as brick. One
circumstance appeared inexplicable to Réaumur and his friend Du Hamel,
who studied the operations of these insects in concert. After taking a
portion of sand from one part of the garden-walk, the bees usually took
another portion from a spot almost twenty and sometimes a hundred paces
off, though the sand, so far as could be judged by close examination,
was precisely the same in the two places. We should be disposed to
refer this more to the restless character of the insect than to any
difference in the sand. We have observed a wasp paring the outside of
a plank, for materials to form its nest; and though the plank was as
uniform in the qualities of its surface, nay, probably more so than the
sand could be, the wasp fidgeted about, nibbling a fibre from one, and
a fibre from another portion, till enough was procured for one load. In
the same way, the whole tribe of wasps and bees flit restlessly from
flower to flower, not unfrequently revisiting the same blossom, again
and again, within a few seconds. It appears to us, indeed, to be far
from improbable, that this very restlessness and irritability may be
one of the springs of their unceasing industry.
By observing, with some care, the bees which we found digging the clay,
we discovered one of them (_Osmia bicornis_) at work upon a nest, about
a gunshot from the bank. The place it had chosen was the inner wall of
a coal-house, facing the south-west, the brick-work of which was but
roughly finished. In an upright interstice of half an inch in width,
between two of the bricks, we found the little architect assiduously
building its walls. The bricklayer's mortar had either partly fallen
out, or been removed by the bee, who had commenced building at the
lower end, and did not build downwards, as the social wasps construct
their cells.
The very different behaviour of the insect here, and at the quarry,
struck us as not a little remarkable. When digging and preparing the
clay, our approach, however near, produced no alarm; the work went on
as if we had been at a distance; and though we were standing close to
the hole, this did not scare away any of the bees upon their arrival
to procure a fresh load. But if we stood near the nest, or even in the
way by which the bee flew to it, she turned back or made a wide circuit
immediately, as if afraid to betray the site of her domicile. We even
observed her turning back, when we were so distant that it could not
reasonably be supposed she was jealous of us; but probably she had
detected some prowling insect depredator, tracking her flight with
designs upon her provision for her future progeny. We imagined we could
perceive not a little art in her jealous caution, for she would alight
on the tiles as if to rest herself; and even when she had entered the
coal-house, she did not go directly to her nest, but again rested on a
shelf, and at other times pretended to examine several crevices in the
wall, at some distance from the nest. But when there was nothing to
alarm her, she flew directly to the spot, and began eagerly to add to
the building.
It is in instances such as these, which exhibit the adaptation
of instinct to circumstances, that our reason finds the greatest
difficulty in explaining the governing principle of the minds of the
inferior animals. The mason-bee makes her nest by an invariable rule;
the model is in her mind, as it has been in the mind of her race from
their first creation: they have learnt nothing by experience. But
the mode in which they accomplish this task varies according to the
situations in which they are placed. They appear to have a glimmering
of reason, employed as an accessary and instrument of their instinct.
[Illustration: Cells of Mason-Bees, built, in the first and second
figures, by _Osmia bicornis_ between bricks, and in the third, by
_Megachile muraria_ in the fluting of an old pilaster.--About half the
natural size.]
The structure, when finished, consisted of a wall of clay supported by
two contiguous bricks, enclosing six chambers, within each of which
a mass of pollen, rather larger than a cherry-stone, was deposited,
together with an egg, from which in due time a grub was hatched.
Contrary to what has been recorded by preceding naturalists with
respect to other mason-bees, we found the cells in this instance quite
parallel and perpendicular; but it may also be remarked, that the bee
itself was a species altogether different from the one which we have
described above as the _Anthophora retusa_, and agreed with the figure
of the one we caught quarrying the clay--(_Osmia bicornis_).
[In Mr. F. Smith's elaborate catalogue of the British hymenoptera there
is a most interesting account of the habits of this insect, which is
the most abundant species of the genus, and is spread not only over the
whole of England, but over the continent, being found as far south as
Italy and as far north as Lapland.
"In a hilly country, or at the sea-side, it chooses the sunny side of
cliffs or sandy banks in which to form its burrows, but in cultivated
districts, particularly if the soil be clayey, it selects a decayed
tree, preferring the stump of an old willow. It lays up a store of
pollen and honey for the larvæ, which when full grown, spins a tough
dark brown cocoon, in which they remain in the larval state until the
autumn, when the majority change to pupæ, and soon arrive at their
perfect condition. Many, however, pass the winter in the larva state.
In attempting to account for so remarkable a circumstance, all must
be conjecture, but it is not of unfrequent occurrence. This species
frequently makes its burrows in the mortar of old walls."
Another species (_Osmia bicolor_) sometimes makes its cells in very
peculiar situations. When obliged to have recourse to its natural
powers, it uses its limbs right well, attacks the hard sandy banks,
and works at them with the greatest perseverance. But it will not work
one stroke where it can avoid the necessity, and in many cases, it
contrives to avoid work with much ingenuity.
Lying hidden under hedges, bushes, grass, and herbage, are sure to be
shells of various snails, such as the common garden-snail, and the
banded-snail, whose diversified shell is the delight of children. These
shells the bee thinks are as good as ready-made burrows, and she uses
them accordingly.
She goes to the end of the shell, carrying her materials with her, and
then builds a cell, and fills it with pollen and honey. Another cell
is then made, and yet another, until the shell is nearly filled. As
the shell widens, the _Osmia_ places two cells side by side, and when
the insect has worked within a short distance of the mouth, she places
the cells horizontally, so as to fill up the space. There are several
specimens of these curious habitations in the British Museum.
When the whole series of cells is completed, the bee closes up the
entrance with little morsels of earth, bits of stick and little stones,
all strongly glued together with some very adhesive substance.
Another species (_Osmia parietina_) has much simpler habits, and is
much easier satisfied with a dwelling. This insect merely looks out for
a flattish stone lying on the ground, and crawls under it to see if
there is any hollow. If so, it attaches the cocoons to the stone and
leaves them. On one stone, seen in the British Museum, no less than two
hundred and thirty cocoons were placed, although the stone is only ten
inches in length by six in width.
This insect is almost wholly confined to the north of England.]
There was one circumstance attending the proceedings of this mason-bee
which struck us not a little, though we could not explain it to our own
satisfaction. Every time she left her nest for the purpose of procuring
a fresh supply of materials, she paid a regular visit to the blossoms
of a lilac-tree which grew near. Had these blossoms afforded a supply
of pollen, with which she could have replenished her cells, we could
have easily understood her design; but the pollen of the lilac is not
suitable for this purpose, and that she had never used it was proved
by all the pollen in the cells being yellow, whereas that of the lilac
is of the same pale purple colour as the flowers. Besides, she did not
return immediately from the lilac-tree to the building, but always
went for a load of clay. There seemed to us, therefore, to be only
two ways to explain the circumstance:--she must either have applied
to the lilac-blossoms to obtain a refreshment of honey, or to procure
glutinous materials to mix with the clay.
When employed upon the building itself, the bee exhibited the restless
disposition peculiar to most hymenopterous[P] insects; for she did not
go on with one particular portion of her wall, but ran about from place
to place every time she came to work. At first, when we saw her running
from the bottom to the top of her building, we naturally imagined
that she went up for some of the bricklayer's mortar to mix with her
own materials; but upon minutely examining the walls afterwards, no
lime could be discovered in their structure similar to that which was
apparent in the nest found in the wall of Greenwich Park.
Réaumur mentions another sort of mason-bee, which selects a small
cavity in a stone, in which she forms her nest of garden-mould
moistened with gluten, and afterwards closes the whole with the same
material.
[Illustration: Cells of _Chalicodoma_.]
[In the accompanying illustration is shown a series of cells which are
constructed by an insect which is closely related to the rose-cutter
bee of our own country, to which it bears a close resemblance.
It is a native of South Africa, and its name is _Chalicodoma
coelocerus_. The insect is about half an inch in length, and the colour
of the head and body is black, that of the abdomen being brick red.
The nest is made of mud, which is collected by the patient insect and
stuck against walls, trunks of trees, and similar localities. In this
lump of mud the insect excavates a small number of burrows, each of
which contains several cells. If the reader will refer to the central
burrow, he will see that it is divided into three cells. The specimen
from which this drawing is taken may be seen in the British Museum.
There is another South African insect which makes its mud nest, and
fastens it against trees and walls. This is called _Synagris calida_,
and its colour is almost dingy black, the only exception being the red
tip to the abdomen. The holes seen in the engraving are the apertures
through which the young brood has escaped into the world. The nest is
represented of half its natural size.]
[Illustration]
Mining-Bees.
A very small sort of bees (_Andrenæ_), many of them not larger than a
house-fly, dig in the ground tubular galleries little wider than the
diameter of their own bodies. Samouelle says, that all of them seem
to prefer a southern aspect; but we have found them in banks facing
the east, and even the north. Immediately above the spot where we have
described the mason-bees quarrying the clay, we observed several holes,
about the diameter of the stalk of a tobacco-pipe, into which those
little bees were seen passing. The clay here was very hard; and on
passing a straw into the hole as a director, and digging down for six
or eight inches, a very smooth circular gallery was found, terminating
in a thimble-shaped horizontal chamber, almost at right angles to the
entrance and nearly twice as wide. In this chamber there was a ball
of bright yellow pollen, as round as a garden pea, and rather larger,
upon which a small white grub was feeding; and to which the mother
bee had been adding, as she had just entered a minute before with
her thighs loaded with pollen. That it was not the male, the load of
pollen determined; for the male has no apparatus for collecting or
transporting it. The whole labour of digging the nest and providing
food for the young is performed by the female. The females of the
solitary bees have no assistance in their tasks. The males are idle;
and the females are unprovided with labourers, such as the queens of
the hive command.
[Illustration: Cell of Mining-Bee (_Andrena_).--About half the natural
size.]
Réaumur mentions that the bees of this sort, whose operations he
had observed, piled up at the entrance of their galleries the earth
which they had scooped out from the interior; and when the grub was
hatched, and properly provided with food, the earth was again employed
to close up the passage, in order to prevent the intrusion of ants,
ichneumon-flies, or other depredators. In those which we have observed,
this was not the case; but every species differs from another in some
little peculiarity, though they agree in the general principles of
their operations.
[The genus Andrena is an exceedingly large one, nearly seventy species
being acknowledged in England alone. They choose various situations
for their nest; a very favourite situation is a hard-trodden pathway;
into this the bees burrow for some six or seven inches, and often drive
their tunnels to a depth of ten inches. Digging up these habitations
is not a very easy task, because the tunnel does not run straight, but
turns aside when a stone or any similar obstacle comes in the way, and
in getting out the stone the burrow is mostly broken. The only method
of digging out the nest successfully is either by pushing a small twig
up the hole, and using it as a guide, or by filling the entire hole
with cotton wool, so as to prevent the earth from falling in.
The commonest species is _Andrena albicans_. Its length is rather
less than half an inch, and its colour is black, with a thick coating
of rich red hair on the upper part of the thorax. This species is
plentiful on the continent, and is found as far south as Italy. But it
is equally capable of enduring great cold, as it has been captured in
the Arctic regions. Sometimes the bee will not trouble itself to make a
number of separate burrows, but will drive short supplementary tunnels
from the side of the first burrow, so that they all open into one
common entrance.
The Andrenæ are remarkable for the parasites with which they are
infested, the most curious of which is that tiny strepsipterous insect
called the Stylops.
One of the Andrenæ, called _Colletes Daviesana_, is remarkable for the
character of its burrow. Like many of the insects which have already
been described, it seems indifferent whether it burrows in sand-banks
or into the mortar of walls, provided that in the latter case the
mortar is soft and friable.
The insect burrows a hole which is very deep in proportion to its size,
the little bee being only the third of an inch in length, and the
burrows some eight or ten inches in depth. When the mother _Colletes_
has finished her tunnel, she lines the end of it with a thin kind of
membrane, which has been well compared by Mr. F. Smith to goldbeater's
skin. This lining is intended to enable the bee to store honey in the
cell, as, if there were no such protection, the honey would soak in the
ground and be lost.
Having stored up enough food for a single offspring, she shuts it off
by a partition of the same membranous substance as the lining. Her next
care is to make a thimble-like cup at the end, so as to have a double
lining where the honey is to come, and then she puts a fresh supply in
the new cell. This cell is then closed, and the bee proceeds with her
work until she has made from six to eight cells in a single burrow.
This insect suffers terribly from the depredations of the earwig, which
completely empties the burrow both of food and of inhabitants. The
colour of the insect is black, with a little reddish down on the upper
part of the thorax, and some white on the legs. The abdomen is shining
black, but each segment has a very narrow band of reddish down on its
edge.
In 1850, Mr. F. Smith, to whose works such constant reference has been
made, undertook the study of a genus of mining-bees belonging to this
family. The species which he chiefly watched is _Halictus morio_, and
his observations are peculiarly valuable, as showing the wonderful
manner in which the economy of the race is managed. It is known that in
these and many other insects, the pregnant females pass the winter in
a state of hibernation, and begin to work in the following spring, and
that therefore some arrangement must be needful that a supply of such
queens should be kept up.
Mr. Smith found the case to stand thus. Early in April, the females
appeared abundantly, and could be seen until June, but not a single
male was to be found. During June and July, almost all the _Halicti_
had disappeared, the reason being, that the queens had made their
burrows, laid their eggs, stocked their cells, and then died, the
duties of their life having been fulfilled. In the middle of August,
the males began to appear, and in September the females of the first
brood came out. They immediately set to work at their burrows, and
laid their eggs. The ground, thoroughly warmed by the summer sun, soon
hastened the young through their changes, and in an incredibly short
time the insects of the second brood made their appearance. The females
of this brood meet their mates, and then hide themselves until the
following spring.
As in the case of Andrenæ, several tunnels are often made with one
common entrance. The insect is very small, scarcely exceeding the
sixth of an inch in length. The head and thorax are a dark green, the
abdomen is white, and the legs are covered with silvery hairs. It is a
plentiful insect, and is found haunting the holes of old walls.
Passing to another family of British mining-bees, we come to one
species that is remarkable not only for its form, but for its economy.
This is the _Eucera longicornis_, the only known species that inhabits
England. In form it is chiefly remarkable from the fact that the
antennæ of the male are as long as the entire body. The pupa of this
insect is enclosed in a thin membrane, and when the male insect is
about to emerge from its pupal shell, it has recourse to a rather
curious expedient. At the base of the first joint of the front feet
there is a bold notch. When the insect wishes to remove the thin
membranous pellicle which envelopes the antennæ, it lays these organs
in the notch, draws them through, and thus easily strips off the
pellicle. The antennæ are most beautifully formed, the surface of each
joint being marked with an elaborate pattern like net-work, so that
they form beautiful objects for the microscope.
The soil preferred by the _Eucera_ is of a clayey nature. When it has
completed the burrow, it presses the soil at the extremity with all its
might, and smooths it so carefully that the burrow becomes capable of
holding honey without needing any lining. The insect is generally found
about the end of May or beginning of June, and in some places is found
in great numbers. The ground colour of the insect is black, but the
body is covered with a coating of short dun hairs. The length rather
exceeds half an inch.]
_CHAPTER III._
CARPENTER-BEES; CARPENTER-WASPS; UPHOLSTERER-BEES.
Carpenter-Bees.
Among the solitary bees are several British species, which come under
that class called carpenter-bees by M. Réaumur, from the circumstance
of their working in wood, as the mason-bees work in stone. We have
frequently witnessed the operations of these ingenious little workers,
who are particularly partial to posts, palings, and the wood-work of
houses which has become soft by beginning to decay. Wood actually
decayed, or affected by dry-rot, they seem to reject as unfit for their
purposes; but they make no objections to any hole previously drilled,
provided it be not too large; and, like the mason-bees, they not
unfrequently take possession of an old nest, a few repairs being all
that in this case is necessary.