INSTINCT AND INTELLIGENCE
OUR study of the activities of wasps has satisfied us that it is
impracticable to classify them in any simple way. The old notion that
the acts of bees, wasps, and ants were all varying forms of instinct is
no longer tenable, and must give way to a more philosophical view. It
would appear to be quite certain that there are not only instinctive
acts but acts of intelligence as well, and a third variety also—acts
that are probably due to imitation, although whether much or little
intelligence accompanies this imitation is admittedly difficult
to determine. Again, acts that are instinctive in one species may
be intelligent in another, and we may even assert that there is a
considerable variation in the amount of intelligence displayed by
different individuals of the same species. We have met with such
difficulty in our attempts to arrange the activities of wasps in
different groups that we are forced to the conclusion that any scheme
of classification is merely a convenience, useful for purposes of
study or generalization, but not to be taken for an absolutely true
expression of all the facts. This kind of perplexity is well understood
and allowed for in all morphological work, but it has never been fully
realized in the study of habits. The explanation is not far to seek.
The habits of but few animals have been studied in sufficient detail
to bring out the evidence that there is as much variation on the
psychological as on the morphological side, although this field seems
fresh and inviting when compared with the researches of the laboratory.
The necessity of interpreting the actions of animals in terms of our
own consciousness must be always with us. To interpret them at all
we must consider what our own mental states would be under similar
circumstances, our safeguard being to keep always before us the
progressive weakening of the evidence as we apply it to animals whose
structure is less and less like our own.
We arrange the activities of the wasps that we have studied into two
groups, Instincts, and Acts of Intelligence, it being understood that
these classes pass by insensible stages into each other, and that acts
that are purely instinctive when performed for the first time are
probably in some degree modified by individual experience. In this
classification the question of origin is not considered. The facts
are grouped under the two heads, the inferences that they warrant
being left for later consideration. Under the term Instinct we place
all complex acts that are performed previous to experience and in a
similar manner by all members of the same sex and race, leaving out as
non–essential, at this time, the question of whether they are or are
not accompanied by consciousness. Under Intelligence we place those
conscious actions which are more or less modifiable by experience.
It is this power that enables an insect to seek, accept, refuse,
choose,—to decline to make use of this or to turn to account some other
thing. Many writers prefer the term Adaptation for these activities,
and it possesses certain advantages. With these definitions in mind,
let us group the activities of wasps under the two heads.
With the wasps of the genus Pelopæus we were present on several
occasions when the young emerged from the pupa case and gnawed their
way out of the mud cell. They were limp, and their wings had not
perfectly hardened, and yet when we touched them they tried to attack
us, thrusting out the sting and moving the abdomen about in various
directions. These movements were well directed, and, so far as we could
observe, quite as perfect as in the adult wasp. Stinging, then, is an
instinctive act.
The particular method of attack and capture practiced by each species
in securing its prey is instinctive. Ammophila pricks a number of
ganglia along the ventral face of the caterpillar; Pelopæus, we
believe, stabs the spider in the cephalothorax, and probably the
several species of Pompilus do the same. Astata bicolor adopts the same
tactics in capturing her bugs, while it is said of the fly–catchers
that they commonly overcome their victims without using the sting. It
is by instinct, too, that these wasps take their proper food supply,
one worms, another spiders, a third flies, moths, or beetles. So strong
and deeply seated is the preference, that no fly robber ever takes
spiders, nor will the ravisher of the spiders change to beetles or bugs.
[Illustration: PARALYZED SPIDER HUNG UP ON SORREL BY QUINQUENOTATUS
WHILE SHE DIGS HER NEST]
The mode of carrying their booty is a true instinct. Pompilus takes
hold of her spider anywhere, but always drags it over the ground,
walking backward; Oxybelus clasps her fly with the hind legs, while
Bembex uses the second pair to hold hers tightly against the under
side of her thorax. Each works after her own fashion, and in a way
that is uniform for each species.
The capturing of the victim and caring for it before the hole is made,
as in the case of P. quinquenotatus, or the reverse method, pursued by
Astata, Ammophila, Bembex, and others, of preparing the nest before
the food supply is secured, is certainly instinctive; as is also the
way in which some of these wasps act after bringing the prey to the
nest. For example, S. ichneumonea places her grasshopper just at the
entrance to the excavation, and then enters to see that all is right
before dragging it in. Under natural conditions this order is never
varied, although the wasp can adapt herself to different circumstances
when occasion demands. Again, we see Oxybelus scratching open her nest
while on the wing, and entering at once with the fly held tightly in
her legs. Each way is characteristic of the species, and would be an
important part of any definition of the animal based upon its habits.
The general style of the nest depends upon instinct. Trypoxylon uses
hollow passages in trees, posts, straws, or brick walls; Diodontus
americanus, a member of the same family, always burrows in the ground,
as do Bembex, Ammophila, and Sphex. In the case of Trypoxylon the
passage may be ready for use or may require more or less preparation;
the instinctive part is the impulse that requires the insect to use
a certain kind of habitation. Any one familiar with T. rubrocinctum
would never look for her nest in standing stems or under stones; to
use Mr. Morgan’s test, he would be willing to bet on the general style
of the dwelling–place. All of these acts are similarly performed by
individuals of the same sex and race, not in circumstantial detail but
quite in the same way in a broad sense. Variation is always present,
but the tendency to depart from a certain type is not excessive. In
Cerceris the burrow is tortuous, this style of work being common to
many species in the genus, and very characteristic. No Sphex nor
Ammophila constructs any such tunnel. The adherence of all the members
of a species to a certain style of architecture is, then, due to
instinct.
The spinning of the cocoon, in those species in which the larva is
protected in this manner, and its shape, are instinctive. We find that
closely allied species in the same genus make very different cocoons,
as is seen in T. rubrocinctum and T. bidentatum. Some wasps spin no
such covering for themselves. It is a well–known fact that silkworms
sometimes omit the spinning of a cocoon; but this does not affect
the argument, since the descendants of these individuals make the
characteristic covering. Such cases are probably due to individual
variation or perhaps to atavism, this throwing back being not uncommon
among forms that are well known.
Not all of the instinctive acts here enumerated are displayed by each
species studied, although they are common to most of them. We have
doubtless overlooked some activities that should come under this head,
as we have not made a thorough study of any sufficient number of
species to make a final settlement of the matter.
As we have seen with Ammophila and Pelopæus, faults of instinct are
not uncommon, but of all our wasps the one that shows the greatest
aberrations is Pompilus biguttatus. The sandy beach of Lake Michigan is
a favorite nesting–ground with this species, and is the scene of many a
bold robbery, since they are unprincipled little wretches and
“... the good old rule
Sufficeth them, the simple plan
That they should take who have the power
And they should keep who can.”
We once found an unusually tiny biguttatus vainly trying to drag a
large Epeirid which her sting had reduced to helplessness. It was as
though a feeble child should try to move the body of an elephant. The
little wasp clasped one of the spider’s legs firmly in her mandibles,
and then with braced feet and the wildest flutter of wings made gallant
but futile attempts to get it started. Now she lost her hold on the
ground, and wings and legs were all whirling desperately in the air.
Now her feet grasped a loose ball of earth, and, feeling that something
was moving, she renewed her efforts. The pellet was drawn nearer and
began to rotate around the wasp, while she seemed to be under the
impression that she was moving forward. After a few minutes of vigorous
exercise, she paused, perhaps to see how she was getting on, and the
bit of earth rolled away; so that when the attack was renewed, it
was under the old discouraging conditions. She was the impersonation
of perseverance and energy; but after half an hour (no one knows how
long she had been at it before we came) she gave it up, and with many
reluctant circlings flew away. It was probably experiences of this kind
that developed in some of her relatives the habit of digging the grave
under the victim, and thus saving the trouble of transportation.
At another time, we saw a biguttatus trying to run backward with a
little bit of a spider, which she had lifted from the ground and was
carrying in her mandibles,—trying to run backward, because it is
the rule with this genus to move in that way when encumbered with
a load, it being easier to drag a heavy spider than to pick it up
and go forward. The wasp in question was drawn in two directions.
Instinct made her go backward, although in this particular case it was
needless, while she felt a constant desire to turn and go straight
ahead. As a result she waltzed slowly over the sand in a series of
overlapping circles, her head turned toward every point of the compass
in succession, a kind of progress most amusing to the lookers–on.
Biguttatus is not strong enough to fly when laden, but it is the habit
of the species to climb backwards to the top of every obstacle in the
path, and from this vantage point to gain time by taking a downward
flight in the direction of the nest. It is only in the case of tall,
smooth–stemmed plants and grasses that the advantage gained is enough
to repay the trouble of climbing, and we have often thought that the
notion costs the wasp more trouble than it is worth,—as was certainly
the case with one comical little creature that carried the idea to the
extreme of folly. Not only did she scale objects in her way, but just
as old Dr. Johnson felt that he had to touch every tree and post as
he walked along, so when this wasp saw, out of the corner of her eye,
a stone or a plant three or four inches to one side, it called upon
her to climb, and climb she did, although she was obliged to leave her
proper path to do it.
It is obviously more difficult to distinguish actions of intelligence
than of instinct. One must be familiar with the normal conditions of
the insects in question before he is able to note those slight changes
in the environment that offer some opportunity for an adaptation of
means to ends, or before he is competent to devise experiments which
will test their powers in this direction.
We find two classes of intelligent actions among the Hymenoptera which
are sufficiently distinct to be considered separately, although, like
all natural groups, they grade into each other. The first of these
includes those actions that are performed by large numbers in a similar
fashion under like conditions, while in the second class each act is
an individual affair,—as where a single wasp, uninfluenced in any way
by the example of those about it, displays unusual intelligence in
grappling with the affairs of life. Examples of the first class are
found in such modifications of instinct as are shown by Pelopæus and
other wasps in the character of their habitations. Pelopæus, instead of
building in hollow trees or under shelving rocks, as was the ancient
custom of the race, now nests in chimneys, or under the eaves of
buildings. We have found T. rubrocinctum taking advantage of the face
of a straw–stack that had been cut off smoothly as the cattle were fed
through the winter. The same power of adaptation is shown by Fabre’s
experiment with Osmia, in which he took two dozen nests in shells from
a quarry, where the bees had been nesting for centuries, and placed
them in his study along with some empty shells and some hollow stems.
When the bees came out, in the spring, nearly all of them selected the
stalks to build in as being better suited to their use than the shells.
All of these changes are intelligent adaptations to new modes of life,
serving to keep the species in harmony with its surroundings. The
same thing may be seen when a number of social wasps work together to
replace the roof of their nest when it has been torn off.
An instance of the second class is seen in one of our examples of
Pompilus marginatus. This species, while searching for a nesting–place,
leaves its spider lying on the ground or hides it under a lump of
earth, in either of which positions the booty is subject to the attacks
of ants; the wasp in question improved upon the custom of her tribe by
carrying the spider up into a plant and hanging it there. We have now
and then seen a queen of Polistes fusca occupy a comb of the previous
year instead of building a new one for herself,—showing a better
mental equipment than her sisters who were not strong–minded enough to
change their ways, and so built new nests alongside of unoccupied old
ones which were in good condition. In Bembex society it is good form to
close the door on leaving home, but sometimes a wasp will save time by
leaving the entrance open. This, however, is a doubtful case, as the
advantage would, perhaps, be more than balanced by the exposure of the
nest to parasites.
Some years after our first experience with Pompilus scelestus we saw
a wasp of this species carrying her spider home. She dropped it close
to the nest, and looked meditatively, first at the hole and then at
the spider. It was unquestionably going to be a very tight fit, but if
she could get it in that would be an advantage; so after a moment she
seized it by the tip of the abdomen and backing down tried to pull it
after. Tug—_tug!_ No, it would not go down, and scelestus pushed it out
and carried it to a place of safety up among some clover blossoms. She
then washed and brushed herself neatly, and took several little walks,
so that it was fully fifteen minutes before she began to enlarge her
nest. All that time she must have carried in her little scrap of a mind
the idea of doing a necessary act which was outside of her ordinary
routine; and we noted with interest that the change when it was made
accomplished exactly what was needed,—the spider went in, but not too
easily.
In an experiment with a French Sphex which has the habit of laying her
cricket down at the threshold, and going inside for an instant before
dragging it in, Fabre took advantage of the moment that the wasp was
out of sight below to move her prey to a little distance, with the
result that when the wasp came up she brought her cricket to the same
spot and left it as before, while she visited the interior of the nest.
Since he repeated this experiment about forty times and always with the
same result, it seemed fair to draw the conclusion that nothing less
than the performance of a certain series of acts in a certain order
would satisfy her impulse. She must place her prey just so close to
the doorway; she must then descend to examine the nest; and after that
she must at once drag it down, any disturbance of this routine causing
her to refuse to proceed. We once found a Sphex ichneumonea at work
storing her nest, and thought it would be interesting to pursue Fabre’s
method and find out whether she were equally persistent in following
her regular routine. We allowed her to carry in one grasshopper to
establish her normal method of procedure, and found that, bringing it
on the wing, she dropped it about six inches away, ran into the nest,
out again and over to the grasshopper, which she straddled and carried
by the head to the entrance. She then ran down head first, turned
around, came up, and seizing it by the head, pulled it within. On the
following day, when she had brought a grasshopper to the entrance of
the nest, and while she was below, we moved it back five or six inches.
When she came out, she carried it to the same spot and went down as
before. We removed it again, with the same result, and the performance
was repeated a third and a fourth time, but the fifth time that she
had found her prey where we had placed it she seized it by the head,
and going backward dragged it down into the nest without pausing.
On the next day the experiment was repeated. After we had moved the
grasshopper away four times, she carried it into the nest, going head
foremost. On the fourth and last day of our experiment, she replaced
the grasshopper at the door of the nest and ran inside seven times, but
then seized it and dragged it in, going backward. How shall this change
in a long–established custom be explained, except by saying that her
intelligence led her to adapt herself to circumstances? She was enough
of a conservative to prefer the old way, but was not such a slave to
custom as to be unable to vary it.
“It hath been an opinion,” says Lord Bacon, “that the French are wiser
than they seem, while the Spaniards seem wiser than they are.” We leave
it to our readers to determine whether the wasps are wiser than they
seem or seem wiser than they are.
INDEX
INDEX
Agenia, mutilation of spiders, 243, 247.
—— bombycina, 244.
Ammophila, 15;
stinging habits of American and French species, 28;
Fabre’s conclusions contrasted with ours, 52;
sleeping habits noted by Banks, 117.
—— gracilis, great distance over which prey is carried, 46;
failure of instinct, 46.
—— polita, 50.
—— urnaria, 18;
sense of locality, 20;
individuality, 22;
using a pebble as a tool, 38.
—— vulgaris, losing her way, 46.
—— yarrowii, Williston’s notes on habits, 40.
Aphilanthops frigidus, 167;
losing her way, 171;
method of capturing queen ants uncertain, 174.
Aporus fasciatus, 80;
habit of filling up partly made nests, 82;
depends upon close packing to keep spider quiet, 83;
contrast between two individuals, 84.
Ashmead, W. H., on European species of Oxybelus, 78.
Astata bicolor, locality study, 288.
—— unicolor, locality study, 290.
Banks, Nathan, observation on sleeping habits of Ammophila, 117.
Bates, H. W., on habits of Monedula signata, 136.
Belt, Thomas, on locality study of Polistes carnifex, 60.
Bembex labiatus, note on locality sense by Bouvier, 124.
—— rostrata, account of habits by Wesenberg, 139;
note on locality sense by Marchand, 125.
—— spinolæ, 119;
less numerous progeny than other wasps, 120;
habit of feeding young from day to day, 120;
quarrelsome habits, 129;
tolerance of parasites, 132;
number of parasitic larvæ found in nests, 133;
experiment to determine number of nests visited by female at one
time, 139;
teasing Tachysphex, 262.
Bouvier, note on locality sense of Bembex labiatus, 124.
Brehm, on mutilation of spiders by Agenia punctata, 243.
Brues, on sleeping habits of Priononyx atrata, 118.
Cerceris clypeata, 147;
locality study, 149;
experiments on stinging habits, 151.
—— deserta, 152;
locality study, 153.
—— fumipennis, 142.
—— nigrescens, 142.
Ceropales, following Pompilus scelestus, 231.
Chlorion cœruleum, 256.
Crabro interruptus, 102;
locality study, 105.
Crabro lentus, 101;
both flies and bugs found in nests, 101.
—— sexmaculatus, 99;
takes both flies and gnats, 101.
—— stirpicola, 106;
contrasted with other wasps as to manner, 106;
works night and day to finish nest, 108.
—— wesmæli, said to take both flies and bugs, 101.
Dunning, S. W., on finding flies alive in nests of Bembex, 135.
Fabre, J. H., on automatically perfect instincts of Ammophila, 52;
on French species of Sphex, 69;
on the habits of Bembex, 134;
on Philanthus apivorus, 162;
on French species of Pelopæus, 273.
Goureau, on mutilation of spiders by wasps, 244.
Larra quebecensis, 263.
Lubbock, Sir John, on individuality in ants, 288.
Lyroda subita, 253;
feeds her young from day to day, 255.
Marchal, Paul, on poor locality sense of Pompilus seriaceus, 284.
Marchand, observation on locality sense of Bembex rostrata, 125.
Monedula signata, locality study noted by Bates, 136.
Mutilation of spiders by wasps, 243.
Odynerus, variation in nesting habits, 95.
—— anormis, position of egg in nest, 91.
—— capra, 94.
—— conformis, position of egg, 91.
—— perennis, 89.
—— reniformis, position of egg, 90.
—— vagus, wariness, 94.
Oxybelus quadrinotatus, 75;
method of carrying fly, 80.
Passolocus annulatus, 87.
Pelopæus, 265;
individuality, 270;
forgetfulness, 271;
difference between French and American species, 273.
Philanthus apivorus, sucks honey from bee, 162.
—— punctatus, 154;
habits of colony, 156;
experiments on stinging habits, 162;
nesting habits of males, 166.
—— ventilabris, 166.
Plenolocus peckhamii, 95;
stalk invaded by bees and other wasps, 96.
Polistes carnifex, locality study noted by Belt, 60.
Pompilus biguttatus, unreasoning conduct, 298.
—— fuscipennis, 216;
afraid of ants, 219;
biting legs of spider, 220;
sense of locality, 221.
—— marginatus, 221;
capturing spider, 225;
method of digging nest, 229.
—— quinquenotatus, 197;
confined to one species of spider, 202;
nest invaded by small ants, 202;
hangs spider on plant while nest is being made, 204;
robs her neighbors, 211;
loses her way, 214.
—— scelestus, 230;
bites legs of spider, 230;
pursued by parasites, 231;
sleeping habits, 236.
—— seriaceus, poor locality sense noted by Marchal, 284.
—— subviolaceus, following scelestus, 236.
Priononyx atrata, note on sleeping habits, 118.
Rhopalum pedicellatum, 73;
strong power of localization, 73.
—— rubrocinctum, 74.
Social wasps, general habits, 3;
color sense, 5;
sense of smell, 8;
affecting plant distribution, 11;
number in one nest, 12.
Solitary wasps, general habits, 15.
Sphex, habits noted by Fabre, 69.
—— ichneumonea, 56;
nests begun and deserted, 56;
locality study, 58;
intelligence, 305.
Tachysphex tarsata, 261.
Tachytes sp. ?, 248.
—— peptonica, 252.
Trypoxylon, immense numbers of spiders destroyed, 195.
—— albopilosum, 190.
—— bidentatum, 194.
—— rubrocinctum, 180;
protection of nest by male, 181;
male sometimes assists in storing nest, 182;
order in which eggs hatch, 180.
Vespa germanica, 13.
—— maculata, 13.
Wesenberg, on habits of Bembex rostrata, 139.
Wheeler, W. M., on capture of ants by Aphilanthops frigidus, 176.
Williston, S. W., on habits of Ammophila yarrowii, 40.
The Riverside Press
_Electrotyped and printed by H. O. Houghton & Co.
Cambridge, Mass., U. S. A._
FOOTNOTES:
[1] _Introduction to Modern Classification of Insects_, ii, 189.
[2] _Naturalist in Nicaragua_, p. 136.
[3] Fabre says that all of the three species of Sphex that he has
studied lay the egg on this identical place. He places immense
importance on this point, which seems to us rather fanciful. He also
noticed the pulsation of the abdomen and the movements of the other
parts.
[4] Sharp, _Insects_, page 130.
[5] The nest being completed, the wasp went skimming over the ground
as indicated by the line, until the spider, which had previously been
stung and placed upon a leaf, was found. She then dragged it some
distance beyond the nest to the point 2, from which place she took it
to the nest.
[6] The wasp flew from nest to 1, paused a moment, then flew back; then
to 2, paused and flew back; then to 3, paused, then to 4, paused and
flew back to nest; flew to 4, 5, 6, 7, 8, and 9, pausing at each spot,
and flew back to nest along 10; flew, successively, along 11, 12 and
13, resting at the spots designated; from 13 she circled around nest in
direction of arrow points and departed.
[7] The continuous line shows the course walked over by the wasp, the
short marks at right angles representing resting–places; the broken
line indicates flight. Line 1 shows the first study, leading back to
the nest, and line 2 the second, ending in flight and departure.
[8] _Ants, Bees, and Wasps_, p. 95.
[9] The continuous line shows the course walked over by the wasp; the
short marks at a right angle indicate resting–places; the broken line
indicates flight.
TRANSCRIBER’S NOTE:
—Obvious print and punctuation errors were corrected.