Supplement to Harvesting Ants and Trap-door Spiders.
J. Traherne Moggridge
Transcriber's Note: Text emphasis denoted as _Italic_ and =Bold=.
Whole numbers and fractional parts as 123-4/5.
SUPPLEMENT
TO
HARVESTING ANTS
AND
TRAP-DOOR SPIDERS.
SUPPLEMENT
TO
HARVESTING ANTS
AND
TRAP-DOOR SPIDERS.
BY
J. TRAHERNE MOGGRIDGE, F.L.S., F.Z.S.
_WITH SPECIFIC DESCRIPTIONS OF THE SPIDERS,_
BY THE
REV. O. PICKARD-CAMBRIDGE.
[Illustration]
LONDON:
L. REEVE & CO., 5, HENRIETTA STREET, COVENT GARDEN.
1874.
LONDON:
SAVILL, EDWARDS AND CO., PRINTERS, CHANDOS STREET,
COVENT GARDEN.
CONTENTS.
PAGE
SUPPLEMENT TO HARVESTING ANTS 157
SUPPLEMENT TO TRAP-DOOR SPIDERS 180
SPECIFIC DESCRIPTIONS OF SPIDERS 254
EXPLANATION OF PLATES.
Plate XIII., p. 183, fig. A.--Silk lining of tube of _Atypus
piceus_ (Sulz.), taken at Troyes in Champagne, and
communicated to me by M. E. Simon; B, drawing of portion
of nest of _Cyrtauchenius elongatus_ (Sim.) made after the
description of the discoverer, and subject to his (M. E.
Simon's) corrections. This is the only illustration in the
present work not taken from an actual specimen. These figures
are of the natural size.
Plate XIV., p. 193.--Diagrams of the known types of trap-door nest.
Fig. A, nest of _Atypus piceus_ (Sulz.); B, nest of cork
type; B 1, the layers of silk with earth rims of which a cork
door is composed; C, single-door unbranched wafer type; D,
single-door branched wafer type; E double-door unbranched
wafer type; E 1, lower door of the same, of the natural size;
F, Hyères double-door branched wafer type; F 1, lower door
of the same, of the natural size; G, and G 1, double-door
branched cavity wafer type. At G 1 the perfect type is seen,
while at G, the descending cavity, the outlines of which are
indicated by dotted lines, has been filled up; G 2, lower
door of the same of the natural size. (Figs. A, B, C, D,
E, F, G and G 1, diagrammatic representations of nest on a
reduced scale, Figs. B 1, E 1, F 1 and G 2, of the natural
size).
Plate XV., p. 198, fig. A.--Nest of _Cteniza Californica_ (Camb.)
nearly entire, enclosed in the clayey earth of the bank from
which the specimen was taken, the door being artificially
represented as being partly open; A 1, door of the same as
seen when closed; B, _Cteniza Californica_ (Camb.) from a
living specimen; B 1, the same seen in spirits, the legs not
represented; B 2, the same seen sideways; (figs. A, A 1, B, B
1 and B 2, are of the natural size); B 3, the eyes, greatly
magnified; B 4, the three claws terminating the tarsal joint
of the hindmost left leg; B 5, line representing the measured
length of the spider excluding the falces and spinners, the
uppermost division gives the length of the caput terminating
at the half-moon-shaped fovea, the middle division that of
the thorax, and the lowest that of the abdomen, while the
transverse line gives the breadth of the cephalothorax; B 6,
eggs laid by the spider in captivity on the under side of the
gauze which covered the box (the position is reversed here)
of the natural size; B 7, the same magnified; B 8, another
group of eggs, magnified; B 9, a portion of the same still
more highly magnified; B 10, lines showing measured lengths
of legs of the 1st, 2nd, 3rd, and 4th pairs, and of palpus,
with those of the several joints.
Plate XVI., p. 211, fig. A.--Part of the nest of _Nemesia Simoni_
(Camb.) taken at Bordeaux; A 1, _N. Simoni_ (Camb.) from
life, of the natural size; A 2, the same seen in spirits,
the legs not represented; A 3, the same seen sideways and
magnified; A 4, the eyes, magnified; A 5, the thoracic fovea,
magnified; A 6, line showing measured length of spider, (see
above explanation of fig. B 5, plate XV.); A 7, lines showing
measured lengths of legs of the 1st, 2nd, 3rd, and 4th pairs,
and palpus of spider, with those of the several joints. B,
cephalothorax and abdomen of another specimen of _N. Simoni_,
in which the proportions are different, taken from life, of
the natural size.
Plate XVII., p. 215, fig. A.--Part of the nest of _N. suffusa_
(Camb.) taken at Montpellier; A 1, _N. suffusa_ (Camb.)
from life, of the natural size; A 2, the same in spirits,
seen sideways and magnified, the legs not represented; A
3, another view of the same; A 4, the eyes, magnified; A
5, length of spider (see above, fig. B 5, plate XV.); A 6,
measurements of legs and palpus; B, _N. meridionalis_ (Costa
and Sim.), male, from a specimen in spirits, of the natural
size, legs not represented; B 1, the same magnified; B 2, the
eyes, magnified; B 3, radial and digital joints of the left
palpus with bulb, magnified; B 4, another view of the same,
magnified; B 5, back view of the same, magnified, but less
highly; B 6, length of spider (see above, fig. B 5, plate
XV.); C, _N. meridionalis_ (Costa and Sim.) female, from a
specimen in spirit of wine, of the natural size, legs not
represented; C 1, eyes of the same, magnified; C 2, length of
spider. These two specimens (male and female) were collected
in Corsica, and named by M. E. Simon, who kindly presented
them to me; they are now in the possession of the Rev. O.
Pickard-Cambridge.
Plate XVIII., p. 225, fig. A.--Part of nest of _N. congener_
(Camb.) taken at Hyères; A 1, lower door of this nest viewed
from above, of the natural size; A 2, side view of the same;
A 3, _N. congener_ (Camb.) taken from life, of the natural
size; A 4, side view of the same, enlarged to twice the
natural size, the legs not represented; A 5, cephalothorax
and falces from specimen in spirits, magnified;[108] A 6, the
eyes, magnified; A 7, femur, patella (or genual joint) and
tibia of leg of third pair, showing the three spines on the
outer side of the patella, magnified. B, lower door from a
smaller and younger nest, viewed from above, of the natural
size; B 1, the same viewed sideways.
[Footnote 108: While these pages were passing through the press
(Hyères, Oct. '74), I have had an opportunity of examining 17
additional specimens of _N. congener_. I learn from this that the
pattern represented on the caput in fig. A 5, does not accord with
that in the majority of adult specimens, being usually less defined
and composed of three converging bands. Mr. Pickard-Cambridge's
description (p. 293 below) is, however, quite correct. I may mention
that three spines were present on the patella (genual joint) of legs
III in 16 specimens, the 17th specimen having but a single spine.]
Plate XIX., p. 229, fig. A.--Nest of a young specimen of _N.
Manderstjernæ_ (Ausserer = _N. meridionalis_ Camb., in "Ants
and Spiders," p. 101) from Mentone, showing the descending
cavity, with the lower door pushed across, so as to close
the main tube and join the cavity; A 1, upper portion of
the same, showing the lower door closing the branch. B,
_N. cæmentaria_ (Latr.) from a living specimen taken at
Montpellier; B 1, the same seen in spirits of wine, legs not
represented; B 2, the eyes, magnified; B 3, one of the two
larger claws; and B 4, the small claw of the tarsus of one of
the hindmost legs; B 5, length of spider; B 6, measurements
of legs and palpus. C, the eyes of _N. Moggridgii_ (Camb.)
(= _N. cæmentaria_, Camb., in "Ants and Spiders," p. 92),
magnified. D, _N. incerta_ (Camb.), male, from a specimen
preserved in spirits, collected at Digne in the Basses
Alpes, by M. E. Simon, who kindly lent me the specimen for
examination, represented of twice the natural size, and
without the legs; D 1, another view of the same; D 2, radial
and digital joints of the palpus and palpal bulb, magnified;
D 3, back view of the same; D 4, the eyes magnified. E, eyes
of _N. dubia_ (Camb.), male (= _N. cæmentaria_, Sim.), from
a specimen in spirits, collected in the Pyrénées Orientales,
communicated by M. Simon, magnified; E 1, radial and digital
joints of the palpus with palpal bulb of the same, magnified;
E 2, another view of the same.
Plate XX., p. 254, fig. A, _Cteniza Moggridgii_ (Camb.), male (=
_Ct. fodiens_, Camb., in "Ants and Spiders," p. 89), from
a living specimen taken at Mentone, of the natural size; A
1, the same seen sideways, the legs not represented; A 2,
cephalothorax and falces of the same; A 3, the eyes; A 4,
radial and digital joints and the palpal bulb; A 5, another
view of the same; A 6, one of the two large claws, and A
7, the small claw of the tarsus of one of the legs of the
hindmost pair; A 8, length of the spider and breadth of the
cephalothorax; A 9, measurements of legs and palpus. (Figs.
A 1, A 2, A 3, A 4, A 5, A 6, and A 7, are all magnified.)
B, _N. Manderstjernæ_ (Ausserer), male (= _N. meridionalis_,
Camb., in "Ants and Spiders," p. 101), from a living specimen
taken at Mentone, of the natural size; B 1, the same seen in
spirits and magnified to twice the natural size; B 2, the
same viewed sideways; B 3, the eyes; B 4, tibia, metatarsus
and tarsus of the right leg of the first pair showing the
spine and process on the under and inner side of the enlarged
tibia; B 5, right leg of the third pair showing the three
short spines on the patella; B 6, one of the two large claws,
and B 7, the small claw of the tarsus of one of the legs of
the hindmost pair; B 8, radial and digital joints of palpus
with palpal bulb; B 9, another view of the same; B 10, back
view of the same (figs. B 1 to B 10, all magnified); B
11, measurements of legs and palpus. C, tibia, metatarsus
and tarsus of right leg of _N. Manderstjernæ_ (Ausserer),
male, viewed from the under side and magnified, drawn from
the original specimen belonging to Dr. L. Koch, collected
at Nice, and described as _N. Manderstjernæ_ by Professor
Ausserer. My best thanks are due to Dr. L. Koch for having
enabled me to examine this valuable specimen. [In fig. C,
the curved spine should bend towards, and not away from, the
process on its right and inner side.]
LIST OF SPIDERS DESCRIBED.
Cteniza Moggridgii, sp. n. ♂ p. 254, pl. XX. fig. A.
" Californica, sp. n. ♀ p. 260, pl. XV. fig. B.
Nemesia cæmentaria (Latr.) ♀ p. 264, pl. XIX. fig. B.
" Eleanora (Cambr.) p. 272.
" Moggridgii, sp. n. ♀ p. 273, pl. XIX. fig. C.
" incerta, sp. n. ♂ p. 276, pl. XIX. fig. D.
" dubia, sp. n. ♂ p. 280, pl. XIX. fig. E.
" Manderstjernæ (Auss.) ♂ and ♀ p. 283, pl. XX. fig. B.
" meridionalis (Costa) ♂ and ♀ p. 289, pl. XVII. fig. B.
" congener, sp. n. ♀ p. 292, pl. XVIII. fig. A 3.
" suffusa, sp. n. ♀ p. 295, pl. XVII. fig. A 1.
" Simoni, sp. n. ♀ p. 297, pl. XVI. fig. A 1.
SUPPLEMENT TO HARVESTING ANTS.
During the short time which has elapsed since _Harvesting Ants and
Trap-door Spiders_ left the printer's hands, fresh material has
rapidly accumulated, and an assiduous search after these creatures,
and the continued study of their works and ways, has met with ample
reward and encouragement.
It was my wish, when originally publishing these observations, many
of which were due to the active co-operation of friends, to invite
my readers to take part with me in my pleasure and pursuits, so
that we should from that time work together, and, by communicating
our discoveries to each other, increase our knowledge, and at the
same time enlarge the field of our research. My intention was
that we should leave to others the necessary work of collection,
preservation, and arrangement, and that, while our fellow naturalists
pin specimens into classified cabinets, and devote long hours to the
description of peculiarities of form and colour, we should undertake
the lighter task of complementing their labours by observing and
recording the habits and conditions of existence of the creatures
themselves.
Looked at in this light, the present pages and those of the
preceding work may be regarded as so many drawers in our _Cabinet
of Habits_, and though, as we open drawer after drawer, many gaps
and blank spaces remind us how much remains to be done in order to
complete the collection, yet the interest and suggestiveness of
the specimen-facts already secured, should encourage and direct us
onwards. There have not been wanting instances in which my readers
have associated themselves with me in the way indicated, and it is
with pleasure, when reviewing the entire work, that I recall how
many of its most interesting features are due to the researches and
assistance of friends,[109] and commemorate at once their discoveries
and unfailing kindness. I had certainly expected that before this
time some new species of harvesting ants would have been discovered,
either on the Riviera, where attention has been especially called to
the subject, or in other parts of Europe, where dissimilar conditions
might have been expected to be associated with a different fauna; but
this has hitherto not been the case.
[Footnote 109: To all who have rendered me this valuable help I tender
my cordial thanks. I am under very special obligations to Mr.
Pickard-Cambridge, for descriptions of spiders, and to Mr. F. Smith
for the names of the Ants; assistance which I should have found it
almost impossible to dispense with or to replace.]
One might naturally suppose that if harvesting ants were discovered
in localities very widely distant from each other, they would prove
to belong to different species, but thus far, both in Europe and
Northern Africa, it is the same two well-known species of _Atta
barbara_ and _A. structor_ that constantly reappear.
For instance, I have recently learned that harvesting ants are found
at Cadenabbia on the lake of Como, and at Montpellier in Southern
France; but on examination, the ants from the former place are
clearly seen to belong to the species _structor_, and those from
Montpellier to the two species _structor_ and _barbara_.
I was greatly interested to receive specimens of ants, and of the
seeds which they were carrying and storing beneath the stones of a
paved road at Cadenabbia, for this is the northernmost point[110] at
which the habit of harvesting has as yet been noted. This discovery
suggests the possibility of the occurrence of the habit in the warmer
and more sheltered of the Swiss valleys. When at Montpellier in May
last I frequently observed long trains of ants bringing seeds and
small dry fruits to their nests, but these harvesters also turned
out on close inspection to be _Atta structor_ and _A. barbara_,
with its red-headed variety. These, it will be remembered, are the
only species of European ants which have as yet been proved to be
harvesters and seed-storers in the fullest sense of the term, that is
to say, which not only gather and carry seeds, but also store them in
large quantities below the surface of the ground.[111]
[Footnote 110: I have related in a note at the foot of p. 4 in _Ants
and Spiders_ how _Formica nigra_ in England, though paying no
attention to seeds generally, will sometimes collect the fresh seeds
of the sweet violet (_Viola odorata_).
When I published this account I was quite unaware that the fact that
certain English ants collect sweet violet seeds had been observed by
Mr. R. Wakefield forty years before.
This was communicated by Mr. Wakefield in a letter to Mr. John
Curtis, the substance of which was read before the Linnean Society
in 1854, and published in their Proceedings (see Proceedings of the
Linnean Society, ii. 293), where we read: "He (Mr. Wakefield) states
that he has seen the black species (_Formica nigra_, L.) for days and
nights together industriously occupied in dragging to its cells the
seeds of the common violet (_Viola odorata_, L.)
"He first noticed this fact on the 3rd of July, 1832; and he regards
it as a curious subject of inquiry for what purpose, if not for
their own future provision, they could accumulate these stores?" Mr.
Wakefield appears to accept this as evidence that these ants possess
the habit of storing seeds; but this is not so, as will be seen by
reference to my note alluded to above, and I am inclined to believe
that they collect these particular seeds either under the mistaken
belief that they are larvæ, to which when fresh they bear some
resemblance, or for the sake of some juices which they may obtain
from the fleshy appendage attached to the seed.]
[Footnote 111: Six other species belonging to the genus _Atta_ are
found in Europe, but they are all unknown to me.
It seems likely that, if other harvesting ants do exist in Europe
they may belong to one of these six species; for we have seen (_Ants
and Spiders_, p. 59) that all the ants which are known to possess
this habit are either members of the genus _Atta_ or belong to genera
closely related to it.]
In the case of _Pheidole megacephala_ (the only other European ant
which I have detected collecting seeds in large numbers), I have
never been able to find granaries or subterranean stores of any
kind, though I have frequently made extensive search for them, and
explored, to all appearance, the whole nest.
When we remember the great variety of ants which inhabit Europe alone
(a recent list[112] enumerating no fewer than 104 distinct species),
it certainly may seem strange at first that only two of their number
should possess this habit. Perhaps, however, we may yet discover
that some other of these species are true harvesters; but at present
the chances seem rather against it, since the harvesters found at
such distant points as Algiers, Cadenabbia, and Montpellier have all
turned out to belong to one or other of the two species, _structor_
or _barbara_.
[Footnote 112: _Description des Fourmis d'Europe pour servir à l'étude
des insectes myrmecophilis_, by Ernest André, in _Rev. et Mag. de
Zool._ 3^{e} ser. tom. ii. (1874), p. 152, &c.]
Indeed it may very well be that the numerical superiority and wide
distribution of these two species have served to secure to them a
more or less exclusive right to the habit of harvesting, for it
is clear that a given tract of country can only afford supplies of
grain to a limited number of colonies; so that, if these ants have
taken up the ground and are strong enough to maintain possession, no
others would have a chance. However this may be, I find that the more
insight I gain into the distinctive habits and relations of animals,
the more the belief impresses itself upon me that wherever we find
many closely-allied species inhabiting restricted areas, there we may
safely look for important differences among these species in respect
of their modes of life, and in the development of their instinct and
intelligence. And indeed this may be considered as a corollary of
the great law of natural selection, which uniformly tends to secure
the greatest possible amount of divergence in this respect, and to
prevent the co-existence in close proximity to each other of distinct
species having the same requirements and manner of life.
Thus, for example, even _Atta barbara_ and _structor_, though most
closely related as species, differ in habit; the former leading a
much more active life during the winter months at Mentone than the
latter, and seeking its home rather in wild than cultivated ground.
Then what differences different ants present in respect of strength,
speed, powers of offence and defence, numerical strength of colonies,
timidity, date and frequency of departure of winged ants from the
nest, odour emitted, combativeness, architecture and selection of
localities, nature of food, nocturnal and diurnal habits, and in
many other properties and conditions! It is doubtless owing to
dissimilarity in these and other respects that it becomes possible
for so many species to co-exist within very narrow limits, so that
even three or four distinct kinds sometimes form their nests so close
to each other that their galleries interlace and almost touch.
There are probably very few conditions of life (except those
concerned with the nature and manner of obtaining food) which have a
greater influence either in keeping creatures apart or in bringing
them into collision, than those which constitute differences in their
respective periods of activity and development. Thus, two species of
which one has nocturnal and the other diurnal habits, or of which
one is dormant while the other is active, may be said to travel
different roads and to be complete strangers to one another. Complete
separation of this kind is, of course, not the rule, and the greater
number of species find themselves in more or less constant rivalry,
but possess a sufficient number of points of dissimilarity in habit
and requirements to make their co-existence possible.
It is curious to note what little differences, as they seem to us,
may determine the fate of an ant. For example, the lizards will
lie in wait for and greedily seize and devour the winged males and
females of _structor_ and _barbara_, though they dare not attack the
assembled workers. It is curious to watch the way in which these
worker ants will protect the winged ants which are about to leave
the nest, by gathering round and swarming over them. When, as often
happens, the nest is placed in an old terrace-wall, one may see the
lizards creeping along or lying moulded into the inequalities of the
stones, all having their eager eyes directed towards the swarm. One
may then see the worker ants walk with impunity straight up to the
very noses of the lizards, while the male or female which should
chance to straggle in the same direction would infallibly be eaten
up. The lizards plainly show their fear of the workers by the way in
which, when they make up their mind to try a dash at some outlying
part of the ant colony, they leap through the lines in the utmost
haste as if traversing a ring of fire.
Now these worker ants are destitute of stings, and I can only suppose
that their power of combination, stronger jaws and more horny coats,
have gained them this immunity. I remarked that the smaller lizards
appeared to have some difficulty in dealing with the males and
females which they captured, and would beat and pound them against
the stones before devouring them, while the larger ones would often
make but one mouthful of them, swallowing wings and all!
If it were not for this body-guard of workers it is difficult to
see how the males and females in such situations could ever escape.
It is also plain that if the worker harvesting ants were as liable
to be seized and devoured as their winged companions, the species
would soon become extinct, for they expose themselves more than ants
ordinarily do, and their long provision-laden trains would be almost
at the mercy of any enemy which could attack them without fear of
results.[113]
[Footnote 113: Speaking of the enemies of ants, I may mention having
seen a young robin in England picking up and swallowing the workers
of _Formica nigra_ just as if they were crumbs. I knew that birds
would eat the male and female ants, but I had thought the workers
were exempt from their attacks, and, indeed, they must be so as a
rule, for otherwise they would speedily become extinct.]
Remembering this, it is interesting to note how differently the
tiger-beetle (_Cicendela_) behaves when hunting the powerful
harvesting ants and when preying upon the weak little _Formica
(Tapinoma) erratica_; for, while it seizes the latter without taking
any precautions, it is evidently more than half afraid of the former.
I have seen this beetle lying in wait near a train of _structor_ or
_barbara_ ants, watching until some individual separated a little
from the main body, when it would rush forward and make a snap at it,
retiring again as quickly as it came. If the tiger-beetle fails to
seize its prey exactly behind the head it will let it go again, and
two or three ants are often thus cruelly mutilated before a single
one is carried off.
No doubt the beetle has learned that if once this ant clasps its
mandibles upon either antennæ or legs, nothing, not even death
itself, will make it release its hold. It therefore tries to pin the
ant in such a way that it cannot use its formidable jaws. Perhaps the
habit of forming long compact trains may have been acquired by the
ants partly with a view to guarding against attacks of this kind.
The colonies of the little _F. erratica_, on the other hand,
apparently have to trust to their habit of working under the covered
ways which they construct, as well as to their activity and great
numbers for their preservation.
I had thought that the very powerful, and, to me, disagreeable, odour
of these little ants might have rendered them distasteful to the
tiger-beetle, but this is evidently not the case.
I have said above that, as far as our present knowledge goes, only
two out of the 104 species of European ants are possessed of the
habit of collecting and storing seed, and it may be reasonably asked
how it can have come about, if this is the case, that the ancient
authors were so well acquainted with the fact.
The explanation is that these writers lived on the shores of
the Mediterranean, where these two species--_Atta barbara_ and
_structor_--are extremely common objects, both on account of their
abundance and their habits. The long trains of harvesters remain
exposed to view for hours together, and _structor_ seeks the
neighbourhood or even the interior of towns, so that these ants
arrest the attention even of the unobservant, and often become
familiar as the sparrows.
There can be little doubt that these two ants display the same habits
throughout all the warmer districts which they inhabit, but whether
they do so in Switzerland, Germany, Northern France, and the other
colder portions of their range, remains one of the many interesting
questions which still await investigation.
Mr. F. Smith has recorded the presence of _Atta barbara_ in
Palestine, and I have lately obtained some curious evidence which
goes to show that harvesting ants not only carried on their
operations in times past in that country, but that their seed-stores
were on a much larger scale than any I have observed on the Riviera.
I am indebted to Dr. F. A. Pratt for the information that mention
was made of ants and their stores in the Misna, that codification of
the traditionary and unwritten laws of the Jews, which was commenced
after the birth of Christ under the presidency of Hillel, and which
has at least the merit of serving as a record of a multitude of very
ancient customs and observances which, but for it, would probably
have long ago been forgotten.
Now it so happens that the very first section of the Misna is called
_Zeraim_, and has to do with seeds and crops, and I was thus enabled,
without any very prolonged search, to light upon one of the passages
in question.[114] It occurs in a chapter entitled _De Angulo_ in the
Latin version, treating of the _corner_ of the fields bearing crops
which should be set aside for the poor, and of the rights of the
gleaners, and may be freely rendered as follows: "The granaries of
ants (_Formicarum cavernulæ_), which may be found in the midst of a
growing crop of corn, shall belong to the owner of the crop; but, if
these granaries are found after the reapers have passed, the upper
part (of each heap contained in these granaries) shall go to the poor
and the lower to the proprietor." And then is added: "The Rabbi Meir
is of opinion that the whole should go to the poor, because whenever
any doubt arises about a question of gleaning the doubt is to be
given in favour of the gleaner."
[Footnote 114: "Formicarum cavernulæ in media segete proprietarii
censentur; pone messores superiore parte pauperum, inferiore
proprietarii. R. Meir totum pauperum esse censet, quia quod dubium
est in spicelegio, spicilegium est." And to this the following
explanatory note is appended: "Formicarum cavernulæ, Frumentum inibi
repertum." Misna, Sect. I. Zeraim. Cap. IV. p. 25. Latine vertit et
commentario illustravit Gulielmus Guisius. _Accedit_ Mosis Maimonidis
_Præfatio in_ Misnam, Edo. Pocockio _Interprete_, Oxoniæ A.D. 1690.]
The intention of this very quaint bit of legislation, or rather
of the ancient custom which gave rise to it, appears to have been
the following; it was to settle once and for all a nice point of
conscience with reference to the claims of the poor upon these ant
stores. If the heaps of grain were found among the standing corn
before the reapers reached the spot or while they were still at
work, the proprietor might claim them without any hesitation; but,
if they were discovered after the passing of the reapers, then it
was conceivable that the ants, which during the whole time had never
ceased their labours, might have collected some of the grain from the
fallen ears of corn which lay upon the ground, and were the property
of the gleaners. These grains would be those which the ants had
collected most recently, and would therefore lie on the surface of
each granary heap. Thus it was settled that the upper portion of each
heap should belong to the poor, and the lower, that collected from
the standing crop, to the proprietor.
We may perhaps laugh at the notion of critically discussing and
legislating upon such a subject, and think that such a pitiful matter
might have been allowed to pass among those _minima_ about which even
the Jewish law need not care.
Be this as it may, it is interesting for us to learn that a custom of
the kind had its place among the recognised traditions of the people,
and that the harvesting ants of Syria had earned a place in these
records by amassing stores of sufficient size, and so disposed as to
make them worth collecting.
This reminds us of what M. Germain de St. Pierre has related (_Ants
and Spiders_, p. 29) of the extent of the depredations made among the
corn crops at Hyères by these ants; and doubtless other observers who
have opportunities for watching the ants during the summer months
might supply further confirmation.
It would be of interest to learn the extent and manner of concealment
of these large stores of grain, but, during the months from October
to May, I have never seen corn in any quantity in the granaries,
though there was frequent evidence of its late presence in the
dense masses of husks of oats and other large grain lying near the
nests. In October, 1873, I found near the entrances to a nest of
_structor_ a circular mound formed of this refuse, twenty-seven
inches in diameter, and averaging two inches in thickness, while
near other nests I have found the chinks between the stones of the
terrace-wall behind which the nest lay, literally stuffed with husks.
It was plain that these grains of cereals and the larger grasses
had been collected during the summer. The granaries in the winter
and spring contain the grains of some few of the autumnal grasses,
but are principally filled with seeds of the other more abundant
autumn-fruiting plants belonging to the neighbourhood.
I have now collected from the granaries of these ants the seeds or
small dry fruits of fifty-four distinct species of wild plants, and
on examination I find that during my stay in the south (from October
to May) the seeds of the distinctively spring and summer-flowering
plants are either entirely absent or are very scarce, while the
great bulk of the seeds belong to plants which ripen their fruits
in the autumn. Thus the grains of oats, of the large fescue and
brome grasses, of quaking grasses (_Melica_), and other kinds common
near the nests in May, are conspicuously absent in the winter, as
are the fruits of all the sedges but one, and this one (_Carex
distans_) retains its fruits till late in the autumn. Among other
spring-flowering plants common near the nests, the seeds of which
are also absent, I may mention violets (_Viola odorata_), poppies,
(_Papaver_), certain species of _Veronica_, _Helianthemum guttatum_,
_Silene quinque-vulnera_ and _Plantago Bellardi_.
Here a curious question arises--viz., What becomes of the large
stores of seeds which one may still find in the nests in May, when
the ants are busy pouring fresh supplies into the nest? The answer
probably is, that, as the weather becomes warmer, ever-increasing
calls are made by the larvæ upon the food-resources of the nest, and
that old and new seeds rapidly disappear together, and all the energy
and activity of the colony is needed to meet the increased demand.
Still, it would be interesting, if it were possible, to assure
oneself whether this is the case; that is to say, whether the
residue of the winter stores is really consumed during the summer,
or whether a portion of it remains in the granaries until the
following autumn. One might perhaps learn something as to this if
one had an opportunity of opening a nest late in July, and before
the characteristic autumn-fruiting plants had set their seed. If the
granaries were then principally filled with seeds of spring-fruiting
plants, and the winter seeds were almost or entirely absent, this
would afford tolerably good negative evidence in favour of the latter
having been eaten during the summer.
One thing is certain, and that is, that these harvesting ants do not
habitually abandon their nests every year. On the contrary, while
many swarms leave the nests at different seasons, a portion of the
original colony, or of its descendants, still remains in the old
home, and very few out of the many nests which I have watched during
the past three years, and of which I have noted and mapped the
positions, have been deserted. On my return to Mentone in October,
1873, I hastened to examine the nests between which war had been
carried on in the previous year (_Ants and Spiders_, p. 38), and
found in one case that the vanquished nest was completely lifeless
and abandoned, while the victorious colony was remarkably thriving,
and its granaries teemed with seeds. The locality occupied by the
other belligerent colonies had unfortunately been built over.
I have often been asked whether I could give an approximate estimate
of the quantity of seeds contained in a nest of average size, but
I have hitherto felt unable to do this in a satisfactory manner. I
am now in possession of more reliable data, and believe that the
following calculation may be taken as a near approximation to the
truth. During the spring of 1873 I removed with but very little loss
the contents of two granaries from a very extensive nest of _Atta
structor_, consisting principally of seeds of clover, fumitory, and
pellitory. These seeds, when perfectly clean and freed from earth,
weighed in the one case 4 sc. 4 grs., and in the other 5 sc. 8 grs.
Now there cannot have been less than eighty such granaries in this
nest, so that, if we take five scruples as the average weight of the
seeds in each granary, and this, allowing for loss in collection,
which we may fairly do, we should have a total weight of more than
sixteen ounces, or one pound avoirdupois weight of seeds contained
in the nest. But, though this mass of seeds represents the result
of infinite labour on the part of the ants, each individual granary
contains but an insignificant quantity, and the store-chambers often
lie at great distances apart; it is therefore impossible to believe
that the stores alluded to in the Misna can have been as small and
scattered as these were, and we must, on the contrary, suppose them
to have been both larger and more accessible.[115]
[Footnote 115: Perhaps these heaps of corn may have been piled up at
the entrance to the nest, as is sometimes the case when the workers,
in their eagerness to secure as much as possible of a passing
harvest, bring in the supplies too fast for their companions within
the nest to be able to find room for and accommodate. When this
happens the seeds lie outside the nest until fresh chambers are
prepared for their reception.]
The means employed by the ants to prevent the germination of the
seeds contained in their granaries still remain secret, and all the
experiments and investigations which I have hitherto been able to
make have failed to give me the clue.
The problem to be solved is the following: Given seeds, the readiness
of which to germinate has been proved, to place them in damp soil at
depths varying from half an inch to twenty inches below the surface
in such a manner that they shall remain there dormant, neither
germinating nor decaying, for weeks and even months. These very seeds
must be capable of germinating after the conclusion of the experiment.
This is what the ants do for millions of seeds, for the instances
in which a few seeds appear to have sprouted within the nest in
defiance of the ants, are very rare and wholly exceptional; and
when after prolonged wet weather germinated seeds are seen outside
the nest, it will usually be found that these have the little root
cut off, and are eventually carried back into the nest and used as
food. By a fortunate chance I have been able to prove that the seeds
will germinate in an undisturbed granary when the ants are prevented
from obtaining access to it; and this goes to show not only that the
structure and nature of the granary chamber is not sufficient of
itself to prevent germination, but also that the presence of the ants
is essential to secure the dormant condition of the seeds.
I discovered in two places portions of distinct nests of _Atta
structor_ which had been isolated owing to the destruction of the
terrace-wall behind which they lay, and there the granaries were
filled up and literally choked with growing seeds, though the earth
in which they lay completely enclosed and concealed them, until by
chance I laid them bare! In one case I knew that the destruction of
the wall had only taken place ten days before, so that the seeds had
sprouted in this interval.
My experiments also tend to confirm this, and to favour the belief
that the non-germination of the seeds is due to some direct influence
voluntarily exercised by the ants, and not merely to the conditions
found in the nest, or to acid vapours which in certain cases are
given off by the ants themselves.
In order to put this latter point to the test of experiment, I
confined about a hundred harvesting ants (_A. structor_), with their
queen and several larvæ, in a glass test-tube eight inches long and
one inch in diameter, closed with a cork and filled up to within
about an inch of the cork with damp sandy soil, most of which was
taken from the ants' nest.
I added six peas, six cress and six millet, and then kept the tube
tightly corked for nine days, only once removing the cork for a few
seconds in order to sprinkle a little water on the ants, which were
evidently in need of it. On the ninth day I turned out the contents
of the tube and found that all the peas, millet and cress, had
germinated and were growing strongly. One of the cress, however, had
had its root, which lay across the gallery constructed by the ants,
gnawed off; four clover seeds, which had come with the soil taken
from the nest, and which had formed part of the ants' stores, had
germinated also. Here the small quantity of air contained in the
test-tube must certainly have become saturated with any vapour which
the ants may be supposed to give off, and we cannot therefore accept
this as the cause of the dormant condition of the granary seeds.
I made other experiments in which harvesting ants were imprisoned
along with various seeds in small, cylindrical, closed vessels
containing a little damp sand. Here the vessels were frequently
rolled from side to side or shaken, during the twenty-two hours for
which the experiment lasted, so as to excite the ants and make them
give off such odours as they possessed, but no trace of injurious
influence was produced upon the seeds, which germinated and grew
normally afterwards.
At Mr. Darwin's suggestion I made a long series of experiments
with formic acid, in which measured quantities, pure or diluted,
were placed in a watch-glass on damp sand and surrounded by seeds,
the whole being enclosed in a covered tumbler, so that the effects
produced on the seeds by the vapour rising from the acid might be
noted. Similar seeds were sown at the same time and in the same
way, but without the acid, so as to permit of comparison. These
experiments have afforded some interesting results,[116] but do not
supply any positive data which might help us to discover the secret
of the ants. They narrow, indeed, the area in which search can
profitably be made, indicating as they do that the vapour of formic
acid is incapable of rendering the seeds dormant after the manner of
the ants, and showing, on the contrary, that its influence is always
injurious to the seeds, even when present only in excessively minute
quantities.
[Footnote 116: I hope shortly to offer these observations, together
with another series of a similar nature in which my friend Mr. J. B.
Andrews has taken part, to the Linnean Society.]
It appears to me now that the most promising field for experiments
made with a view to clearing up this difficulty, is that afforded by
the closer investigation of the phenomena of normal germination, and
by a study of the conditions under which seeds remain dormant, as
they are occasionally known to do, in situations which our general
experience would have selected as favourable to germination.
I have good hopes, also, that when we come to know more of the habits
of harvesting ants in tropical countries, and when naturalists have
excavated and described their subterranean stores--a thing which has
not yet been done as far as I know--we may gather fresh indications
to guide us in our search.
I am puzzled to account for the fact, which I have seen stated by
more than one observer in India, that the ants there have a habit
of bringing out large quantities of grain and seed and laying them
in heaps outside their nests at the commencement of the wet season.
Dr. King, the director of the Royal Botanic Gardens at Calcutta,
has told me that when in the Gwalior territory during the beginning
of the rainy season, he saw heaps of seeds, principally those of a
leguminous plant (_Alyssocarpus_), piled up round the entrances to
the ants' nests, and that it was precisely at that time that flocks
of a rock-grouse (_Pterocles exustus_) first made their appearance.
They fed freely upon the seeds, and Dr. King found the crops of some
of these birds, which he had shot, filled with them.
It is difficult to imagine why these Indian ants should turn out from
their nests the very seeds which it had cost them so much labour to
collect, and the more so as we find that these seeds are devoured
by birds. It seems just possible, however, that the ants, remaining
torpid during the rainy season, do not require the seeds, and know
that, under these circumstances, if left in the nest, they would
sprout, and choke up the galleries and granaries. Perhaps also they
may have learned that a certain number of the ejected seeds will
spring up and afford future harvests within easy reach of the nest.
All this, however, and especially the suggestion as to the dormant
condition of the ants during the rainy season, might easily be proved
or disproved by direct observation; and at present we have nothing
but mere speculation to go upon.
It is curious to find that the native population in a certain part
of India pay a kind of tribute to the ants, for Dr. King informs me
that the Hindoos in Rajputana, a province in which the old traditions
and superstitions retain especial hold, have a custom of scattering
dry rice and sugar for the ants, and thus apparently recognise both
their love of sweet things and their habit of collecting seeds.
It may be that this custom is now little more than a meaningless
rite; but in the past it probably had its origin, either in a wish
to propitiate the good will and avert the destructive attacks of
creatures which are the scourge and dread of entire districts, or in
a sentiment of combined fear and admiration--fear of the power, and
admiration of the energy, forethought, perseverance, and sense of
duty to the community displayed by these marvellous insects.
That the latter feeling may have had some share in prompting this
act is suggested by another custom which is stated[117] to prevail in
Arabia, in accordance with which an ant is placed in the hand of a
newly-born child, in order that its virtues may pass into and possess
the infant.
[Footnote 117: Freytag, paragraph under the Arabic word for Ant, in
his _Lexicon Arabico-Latinum_, vol. iv. p. 339, where he quotes from
a local dictionary.]
Among the many curious and obscure features in the economy of ants,
one of the most interesting is the occasional presence in their nests
of different creatures which live among and often in harmony with
them, the nature of the relations between host and guest being for
the most part quite unknown.
When examining the contents of some granaries from an extensive nest
of _Atta structor_ at Mentone last spring (1874), I found large
numbers of a minute, shining-brown beetle moving about among the
seeds. These little creatures were themselves not unlike some very
small seeds, and were of an elliptic form, measuring a trifle less
than one line in length. They proved to belong to the scarce and very
restricted genus _Coluocera_.[118] This species, named by Kraatz _C.
attæ_, on account of its inhabiting the nests of ants belonging to
the genus _Atta_, has been found in Greece.
[Footnote 118: I am indebted to Mr. F. Smith of the British Museum
for the name of this beetle and for the following reference to its
description; Kraatz in _Berliner Entomologische Zeitschrift_ for
1858-9, p. 140.]
Mr. Bates,[119] in his most interesting account of his travels on the
Amazons, remarks upon the singular fact, of which the above instance
is an example: "that some of the most anomalous forms of Coleopterous
insects are those which live solely in the nests of ants," and he
then goes on to allude to the strange snake _Amphisbæna_, a native
of that region, which also lives in the nests of the Sauba ants
(_Œcodoma cephalotes_), observing how curious it is that an abnormal
form of snakes should be found in the society of these insects. He
is of opinion, however, that the _Amphisbæna_ is not an inoffensive
guest, but lives upon the ants whose nest it selects for its home.
[Footnote 119: _Naturalist on the Amazons_, p. 61-2 (Ed. 2, 1864).]
Another remarkable inhabitant of ants' nests is a minute cricket, of
which I found a single example in the midst of a colony of black ants
at Mentone in February, 1874. This miniature cricket is scarcely as
large as a grain of wheat, the body, excluding the antennæ and other
appendages, measuring only two lines in length. It has been described
by Dr. Paolo Savi[120] under the name of _Gryllus myrmecophilus_. He
detected it in the nests of several species of ants in Tuscany, where
it lived on the best terms with its hosts, playing round their nests
in warm, and retiring into them in stormy weather, while allowing the
ants to carry it from place to place during their migrations.
[Footnote 120: Dr. P. Savi, _Osservazione sopra la Blatta acervorum di
Panzer_ in _Bibliotheco Italiana_, tom. xv. p. 217.]
_Gryllus myrmecophilus_ has also been observed in nests of the turf
ant (_Tetramorium cæspitum_) near Paris.[121]
[Footnote 121: _Bulletin Soc. Entom. de France_ (1872), p. li.]
At Mentone I have never found more than this one specimen, and the
ants among which it was domiciliated were of a species new to me
(_Camponotus_ (_Formica_) _lateralis_, Oliv.). This colony of ants
was composed of many winged males and females, as well as workers,
the last-named measuring from two and a half to three lines in
length, and black in colour. In other colonies I have found the
workers black, with red head and thorax.
Another ant, not enumerated in my list in _Ants and Spiders_, is
_Camponotus_ (_Formica_) _sylvatica_, which I detected in March last
under stones on Cap Martin, near Mentone. When disturbed, this ant
runs along with its abdomen raised vertically in the air, much as
the devil's coachhorse (_Staphylinus_) does. The same curious habit
of erecting the abdomen is found in another ant, not uncommon in
decaying wood in the South, _Crematogaster scutellaris_; and probably
all three insects adopt this threatening attitude, which is that of
the scorpion preparing to strike and sting, in order to intimidate
their enemies, though _Crematogaster_ is the only one which really
possesses a sting.
_Camponotus sylvatica_ has the same long legs and slender body as
_Formica cursor_, and is of about the same size; the workers, which
are of a dark brown colour, measuring about 3-1/2 lines in length.