THE BURROWERS
DUFOUR, in describing the fearful ravages of Cerceris ornata among the
bees, says that the wasps of this genus are among other insects what
eagles and hawks are among birds. While this characterization does not
seem to fit the American species, it is certainly true that the genus
stands out as one of those in which the distinctive peculiarities
are strongly marked. They might be considered the aristocrats in the
world of wasps, their habits of reposeful meditation and their calm,
unhurried ways being far removed from the nervous manners of the
Pompilidæ or the noisy, tumultuous life of Bembex. Their intelligence
is shown by their reluctance to betray their nests, and by their
uneasiness at any slight change in the objects that surround them.
It is not necessary to attempt to catch them or to make threatening
gestures, in order to arouse their sense of danger. If you are sitting
quietly by a nest when the wasp opens her door in the morning she will
notice you at once, and will probably drop out of sight as though she
resented your intrusion into her privacy. After a little she will come
up again and will learn to tolerate you, but at the least movement on
your part, almost at the winking of an eyelid, she will disappear.
[Illustration: NEST OF CERCERIS NIGRESCENS]
Our four representatives of this genus all prey upon beetles that
are injurious to vegetation, and therefore deserve the gratitude of
agriculturists. Nigrescens, with her pale grayish bands, is a very
trying wasp to deal with. We had seen her flying about in the garden
for weeks before we succeeded in tracking her home, and when we did
succeed she was so late about getting up in the morning, stayed away
from home so many hours at a time, and went to bed so early in the
afternoon, that we were not well repaid for watching her nest all day.
Fumipennis, large and handsome, with a broad yellow band at the front
of the abdomen, is another wasp that has no regard for the convenience
of the people who are watching her. You may sit by her big open hole
for hours without seeing her, and when she comes she drops in so
suddenly that, unless you are very much on your guard, you are not sure
even then what she is. Clypeata and deserta are better subjects for
study.
The nests of our species are all deep, tortuous, and very difficult
to excavate. We have never succeeded in finding their pockets; and
yet, for various reasons, we feel perfectly certain that all of them
are like C. ornata in provisioning, successively, a number of cells
which lead out of the main gallery. When one of these cells is filled
with food, and the egg deposited, it is probably closed up, and thus
separated from the runway. From our experience late in the season
with the nests of another wasp, we are inclined to think that we made
a mistake in looking for pockets at the lower end of the tunnel. Had
we searched higher up, at the point of the curve, we might have found
them, the lower part of the gallery probably being designed merely for
a dwelling–place for the mother of the family.
[Illustration: CERCERIS CLYPEATA]
But although we did not get distinct pockets, there was, in at least
one nest, a supply of food that would have far exceeded the wants of a
single larva. We did not succeed in finding eggs on different groups of
beetles; but from a nest into which the wasp was still carrying food we
took a half–grown larva which was identified as being hers. The fact,
too, that a wasp occupies a nest for so long a time as ten days or two
weeks points to the conclusion that she uses it for a number of eggs
which are laid at intervals.
Cerceris digs her nest, deep as it is, all at once. In this she is
a contrast to her near relatives of the genus Philanthus, who busy
themselves for an hour or so every morning with fresh excavations.
On the eighth of July the weather was so warm and bright that we went
down to the garden at half past eight o’clock, knowing that it was
rather early, but hoping that the hot sunshine would tempt the wasps
to industry. We had walked up and down several times, when suddenly,
right in the pathway, a nest appeared. A great quantity of loose earth
had been taken out and heaped up, probably on the preceding day, and
in the midst of this a little hole had been opened since we passed
before. The place looked so promising that we sat down to watch it,
and a few minutes later we were rewarded by a glimpse of some antennæ
down the gallery, and then a little face with yellow markings appeared
but quickly vanished. Now followed a very coquettish performance. The
wasp came slowly creeping up again and again, only to drop out of sight
as soon as she had reached the opening. After a time she grew bolder,
and sat in her doorway, twitching her head this way and that in a very
expressive manner, as though she were planning the work of the day; but
it was plain that although she was up early, business cares were not
weighing heavily upon her mind, for forty minutes passed before she
came out of the nest, and after making three or four circles about the
spot, flew away.
How much livelier and more interesting it would have been if we could
have followed her! We tried to guess at what she was doing, and
imagined her hunting industriously. After fifteen or twenty minutes
it seemed to us that she must have caught something, and that she was
surely returning. Most probably she was not working at all, but was
breakfasting leisurely and exchanging compliments with her neighbors;
for when she did come home after keeping us waiting for an hour and a
half, she brought nothing with her, and seemed quite unconscious of
the fact that greater things had been expected of her.
We had placed a stone upon a dead leaf near by, to mark the
neighborhood of the nest, thinking that even a Cerceris could not
object to so simple an arrangement of natural objects; but our wasp
noticed it at once, and evidently with much suspicion and disapproval.
She began by circling several times just above it. Then she alighted on
it and examined it carefully, walking over it, and creeping underneath,
perhaps to see whether it in any way menaced the safety of her nest,
perhaps as the completion of a locality study made the day before.
She then rose on her wings, and after a little more circling, dropped
suddenly into her hole.
So far we had not been getting on very rapidly, but from this time
things took a turn. Cerceris is never in a hurry, and yet she may be
relied upon to do a certain amount of work every day. The one that we
were now watching had probably come back for a final look at her newly
made nest before beginning to provision it; for she soon reappeared,
and this time really went to work, since in forty minutes she brought
home a beetle which she carried by the snout, venter up, in her
mandibles, supporting it with the second pair of legs while flying. She
was much annoyed at our presence, and circled about as before. Twice
she alighted near by, and walked around for a few minutes, and when she
did this all her feet came down to the ground, the beetle being allowed
to hang loosely. At last she made the best of a bad matter, and went
in. The rest of the morning was occupied with hunting, the capture of
each beetle taking about forty–five minutes. Every time that she came
home she spent fifteen or twenty minutes in the nest.
This species soon became very common, and for two weeks scarcely a
morning passed without our finding at least one newly–made nest. The
study of clypeata, however, consumes a great deal of time. For example,
we found, one morning, two nests within six inches of each other.
It turned out afterward that these were inhabited by two different
wasps; but at the moment we supposed that one of them had been dug and
deserted and then a second one made, and wishing to know which one was
occupied we resolved to watch and see. After waiting for three hours we
saw one wasp returning; but upon noticing us she veered off and began
to circle about. She was heavily laden, and her burden, instead of
being supported by the second pair of legs, as is sometimes the case,
hung down under the thorax and abdomen. After a moment she alighted on
a plant near by, and seemed to consider the situation, then circled
a little more, and flew away, remaining out of sight for fifteen
minutes, then another return, more circlings and hesitations. She
seemed to feel the weight of the beetle now, and alighted frequently
on the ground and walked about; yet she would not go in, so reluctant
was she to betray her nest. In this way she kept us waiting for a whole
hour, although we were not very near to her, and were as still as
statues. At last we retreated, and stood as far back as we could and
still keep the hole in view. She now came closer, and, after hanging
poised on her wings for a moment, dropped into her nest.
We once found a nest of this species in process of construction. A
large heap of fresh earth had been pushed out, which entirely covered
the spot; but at intervals there were upheavals from below which
betrayed the presence of the wasp. When we saw it first it was half
past eight o’clock, and we judged, from what had been accomplished,
that she must have been at work at least an hour. It was half past
nine before the excavation was complete. We had not been certain, up
to this time, as to what we were watching; but now we had the pleasure
of seeing her open her doorway from below and stand in the entrance
while she washed her face with her fore feet, like a cat. When they
rest at the mouth of the hole the first legs, which are yellow, are
bowed in a semicircle on each side of the yellow face, the distal
joints being bent up so that the wasps seem to be standing on their
elbows. This attitude, which is often seen in Bembex spinolæ, gives
them a delightfully amusing, bow–legged appearance. They usually open
their nests in the morning at about nine o’clock,—a little earlier
or later according to the time at which the sun strikes the spot.
Then they spend from forty minutes to an hour in taking a survey, the
least movement on the part of a watcher causing them to drop out of
sight as if the earth had given way beneath them. Sometimes there is
a little way–station an inch or two within the tunnel, and the wasp
falls back only to this point, and here she may be seen, if one peeps
in cautiously, either quietly awaiting the retreat of the intruder, or,
perhaps, performing her toilet in a leisurely and elegant manner.
Whenever she leaves her nest she makes three or four rapid circles
around the spot to freshen her memory of the locality. The most
thorough study that we saw made by clypeata was in the case of the wasp
mentioned before, that was so long in carrying her beetle in because
of our being on the ground. When she finally did go in she stayed only
an instant—just long enough to deposit her load—and then came out and
spent a long time in an investigation of all the surrounding objects,
flying in and out among the plants, now high, now low, and circling
again and again around the spot. It looked as though she had been
puzzled and disturbed by the presence of unaccustomed things. As soon
as the survey was over she went inside and closed the door, as though
its object had been not so much to strengthen her memory as to correct
former impressions.
The work of bringing in beetles goes on very irregularly, and as a rule
not more than two or three are stored in the course of a day. It is
not unusual for clypeata to spend three or four hours away from home
and then come back without anything; and often, even in the middle of
the day, she passes an hour or two in the seclusion of her nest. We
had several nests under observation for a week at a time without ever
once seeing the owners, although they were evidently occupied, since
they were sometimes open and sometimes closed. The outer entrance is
always left open when the wasp goes away, although possibly access
to the pockets may be barred below; but when she enters she closes
the door unless she means to come out again at once. The closing is
sometimes effected by pushing the earth up backwards, with the end of
the abdomen; but the hole is rather too large for this method, and
more frequently the wasp comes up head first, carrying a load of earth
in her front legs. This is placed just within and to one side of the
entrance, and then more armfuls are brought up, until, after two or
three trips, the opening is entirely filled.
We once captured the wasp in a bottle, as she returned, loaded, to the
nest. She dropped the beetle, but soon picked it up again and stung it
vigorously, _with intention_, as the French say, first under the neck,
and then further back, behind the first pair of legs. After this it was
dropped while the wasp fluttered about for a few minutes, but it was
then picked up again, and stung as before. We both saw this operation
repeated in exactly the same way, four different times, with intervals
of five or six minutes between.
In a nest which we excavated after watching it for nine days, we found
nothing until we had gone six inches down, and at this point the
tunnel was lost; but mixed with the crumbly earth that we took out of
the hole, we found eight beetles and a half–grown larva of clypeata.
The destruction of this nest was accomplished one morning, and when
we came back to the spot twenty–four hours later we found that a new
one had been made close by, doubtless by the same individual. We had
expected to find her bringing beetles and dropping them foolishly on
the ground like Paul Marchal’s Cerceris ornata, and were gratified that
she showed an advance in intelligence over that species, although to
be sure she would have been still wiser had she chosen an entirely new
neighborhood. Another individual was so much disturbed by our scrutiny
that she dropped her beetle at the entrance to her nest. She did not
pick it up again and utilize it, although it lay for three days in the
dust at the threshold.
As to the condition of the beetles stored by clypeata: in the first
nest that we opened we found eight, seven of which were dead, while
the eighth, which we had just seen stung several times, was alive, but
died on the following day. The second nest gave us five beetles, all of
them dead and dry. In the other nests that we opened we found nothing,
though we knew that the beetles were there had we only been skillful
enough to discover them.
Of Cerceris deserta, which closely resembles clypeata, but appears
later in the season, we had only a single example. We chanced to see
her dropping into a crevice among some lumps of earth, and at first
could scarcely believe that this was the dwelling–place of a wasp, as
there was nothing whatever about it to indicate a nest; and even after
we had removed the rough pieces of earth above, we could see nothing of
the loose material that must have been carried out.
She was much like clypeata in her manners, with the same habit
of surveying the world from her doorway, and manifesting the same
annoyance at our presence when she was returning to the nest; but she
carried in more beetles in the course of the day and worked much more
rapidly. Between nine and eleven o’clock one morning she brought in
five loads, and some of the journeys occupied only ten minutes.
[Illustration: CERCERIS DESERTA: LOCALITY STUDY BEFORE LEAVING NEST]
The first time that she found us sitting by her nest she circled about
for nearly an hour, seeming unable to make up her mind to enter. At
length we withdrew a little way, but still her suspicions were not
entirely allayed; and after a further study of the situation she
dropped, not into her own nest, but into a large cricket hole near
by. Taken aback by this manœuvre, and thinking that perhaps we had a
second individual to deal with, we stealthily approached, and peering
in, could see the cricket inside, the wasp having slipped beyond. It
did not seem possible that the little creature could be endeavoring to
deceive us, and yet what other explanation could be offered for her
conduct? We again took up our distant position, and after ten minutes
more had the satisfaction of seeing the wasp slip out of the false nest
and drop instantly into the true one. After a little she became quite
accustomed to us, and entered her nest without the least delay.
The prey of deserta is held in the mandibles, and while we were
watching her she did not support it with the second legs, even when
flying.
Philanthus punctatus is a pretty little yellow–banded species much
resembling Cerceris in appearance. The nest consists of a main gallery
with pockets leading from it, each pocket being stored with one egg and
enough bees to nourish a single larva. When the wasps emerge from the
cocoon they find themselves in the company of their nearest relatives
and in possession of a dwelling–place, and they all live together for
a time before starting out independently to seek their fortunes. On
the fifth of August we discovered on the island a happy family of this
kind, consisting of three brothers and four sisters, the females, with
their bright yellow faces and mandibles, being handsomer than the
males. They seemed to be on the most amicable terms with each other,
their only trouble being that while they were all fond of looking out,
the doorway was too small to hold more than one at a time. The nest
was opened in the morning at about nine o’clock, and during the next
thirty or forty minutes their comical little faces would appear, one
after another, each wasp enjoying the view for a few minutes with many
twitchings of the head, and then retreating to make way for another,
perhaps in response to some hint from behind. Then one by one they
would come out, circle about the spot, and depart, sometimes leaving
one of their number to keep house all day alone. They usually left the
hole open; but when there was a wasp within, it was soon closed from
below. During this playtime period they did not return until they were
ready to settle down for the night, the first one coming home at half
after two or three o’clock, and the others arriving at intervals, none
of them staying out later than five. Most commonly they found the right
spot without trouble, scratched open the hole, and then either closed
it behind them or stood waiting in the doorway for the next arrival;
but occasionally they had difficulty in locating the nest, and worked
at two or three different places before finding it.
We kept these wasps under close observation, often watching the nest
from the moment it was opened in the morning until it was closed
at night. On the twelfth of August, a week from the time that we
first saw them, one of the females felt the responsibilities of life
settling down upon her. At half after four in the afternoon she began
to enlarge the nest, and worked with a great deal of energy for forty
minutes. After a long disappearance within the hole she would come up
backwards, kicking behind her a quantity of earth which was not only
taken outside, but was then spread out far and wide. She worked with
the front pair of legs, which were curved inward, after the manner
of Bembex; and when a pebble or some such object came in her way she
either dragged it to a distance with her mandibles or pushed it before
her with her head in a way quite peculiar to herself. In distributing
the earth that was taken out, she went five and one half inches
from the nest—a distance which is much greater than is common among
wasps, but which accords well with the habits of punctatus, since she
continues the work of excavation from day to day.
[Illustration: PHILANTHUS PUNCTATUS]
On August thirteenth, at half after eight in the morning, we found
that a second female, perhaps inspired by the example of her sister,
had made a new nest within two inches of the first one, and had flown
away, leaving it open. Presently the other wasps began to appear, one
after the other, in their doorway. Two of the males flew away, and one
of the females, doubtless the one that we had seen digging the night
before, began to work afresh at making the nest larger. Probably she
was excavating a pocket for the reception of an egg, and the amount
of labor required was enormously increased by the great length (about
twenty–two inches) of the main gallery by which the displaced earth
must be carried out. She worked for an hour, and in spreading the dirt
about, inadvertently filled in the opening of the second nest. At
length she flew away.
At ten o’clock a female arrived carrying a bee, and tried to find
nest No. 2. She came to the wrong place, and worked about, here and
there, for some minutes, holding the bee under the thorax, clasped by
the second pair of legs. Being unsuccessful, she dropped her burden,
and flew away for a few minutes. While she was gone we removed a leaf
that had fallen over her nest, and on her return she at once descended
upon the right spot, and began to scratch open the entrance, the bee
being kicked backward with the rejected earth. When the way was clear,
however, she picked it up, brought it toward the hole, dropped it, ran
in and out, brought it nearer, ran in again, and turning around in
the tunnel, seized the bee in her mandibles and pulled it down. This
performance was due to the accidental obstruction of the gallery, for
we afterward found that punctatus ordinarily flies directly into her
nest, or, when it is closed, pauses on the wing to scratch an opening
with the first legs. The bee is pushed backward a little as she goes
in, but does not often project from under her abdomen.
At fifteen minutes after ten the worker from nest No. 1 brought in a
bee, and from that time the two worked industriously. They showed some
individuality in their ways, for No. 2 always closed her door when she
went away, and never circled at all, while No. 1 invariably circled
before leaving, and always left her nest open. To be sure, there was
a female left on guard, so that perhaps she did not feel the need of
caution.
Our wasps had not far to go for their victims. Forty feet away, on
the eastern side of the island, was a steep declivity, and here, in
the soft crumbly soil, was a great Halictus settlement. No prettier
sight can be imagined than is presented by this colony on every sunny
summer day. The whole bank is riddled with nests, and at the entrance
of each stands a female bee, her tiny head exactly filling the opening.
The bees are constantly arriving, laden with pollen, whereupon the
sentinels politely back inward to make way for them. Into this scene of
contented industry descends the ravaging Philanthus, taking guards and
workers alike.
On the afternoon of the fourteenth of August our two wasps were in
the full tide of affairs. No. 1 took in eleven bees within two hours,
but her record was somewhat confused, as two other females were going
in and out at the same time. We felt sure that neither of these was
hunting, but one of them shared in the labor of the nest by helping
with the work of excavation.
No. 2, however, was alone, so that we could keep a definite account of
her comings and goings. We watched her from half past one until five,
at which hour she came home without a load, and at once closed the nest
for the night, after having stored thirteen bees in three hours and
nine minutes. In some cases the capture of the bee occupied only one,
two, or three minutes, while at other times she was gone much longer.
At each return she stayed only an instant—just long enough to deposit
the bee—inside the nest, and then spent a minute in carefully closing
the hole. The wasps that were going in and out of nest No. 1 sometimes
closed it when they went away, but this was done in an untidy fashion,
quite different from the nicety and precision of No. 2.
At half after five o’clock the wasp that had been digging for some
little time at nest No. 1 flew to nest No. 2, opened it, and attempted
to enter, but was quickly driven out by the owner. She then dug a
little in several other places, finally returning to sleep in the
family home. On the next day we found that No. 2 was tolerating in her
nest one of the females that had not yet begun to hunt, but whether it
was the one she had rejected the night before or the fourth member of
the sisterhood, we could not tell. On the eighteenth, three days later,
the wasp had left this temporary home and made a nest for herself four
feet away on the hillside. The males were still living in the first
nest with two females.
When the weather was cold and cloudy punctatus remained closely housed
within the nest, or, at most, came out to do an hour’s digging, and
then disappeared. The warmer the weather, and the more brilliant the
sunshine, the more rapidly they worked. When leaving the nest they
would often creep out and walk around it three or four times before
rising on their wings, and even then would sometimes alight once or
twice before flying away. The males, especially, liked to stand about
for a time, watching their more industrious sisters at their work. The
females usually began the day with digging, and frequently closed it,
toward night, in the same way.
In order to see the method of stinging, we at one time provided
ourselves with a number of bees, and putting one of them into a bottle,
introduced a wasp. She seized it almost immediately, with great vigor,
and stung it once, under the neck, and then dragged it up and down the
bottle by one antenna which was held in the mandibles. After a moment
she shifted it and held it with the second legs in the usual way. We
now put in another bee, which she also caught, stung in the same place,
and then dropped without relaxing her hold of the first one. As she
seemed to have nothing further to show us we released her, and after
circling a little she took into her nest the bee that she was carrying.
In our next experiment we used a larger glass, thinking that with more
space we might see malaxation. The instant that the wasp was introduced
she grasped the bee with one rapid powerful motion, and stung it
just under the neck as before. Then holding it with the second legs
she began to fly about in the glass. We now introduced another bee,
whereupon the first one was relinquished, and the second was treated
in exactly the same way. The stinging was the beginning and the end of
the operation, and when we released her she at once took the bee into
the nest. There was no malaxation outside, and certainly there was none
within, as was shown by the rapidity with which the wasps issued from
the nest after storing the bees. We were successful in getting the
wasps to sting only when we tried the experiment with those that were
hunting. When those that had not yet begun to store their nests were
put into the glass they paid no attention to the bees.
The victim of the sting of punctatus is killed at once. Life is extinct
from the instant that the stroke is given. This is true also of the
honey–bee that is the victim of Fabre’s Philanthus apivorus; but the
explanation that he gives of the action of his wasp in thus dealing
sudden death instead of paralyzing its foe—that the honey must be
sucked out of the bee before it can be safely used as food for the
larva—does not hold good in our case, since the honey that Halictus
carries to mix with the pollen upon which her offspring are fed, is not
removed.
[Illustration: NEST OF PHILANTHUS PUNCTATUS
A–B, 3½ inches; B–C, 5 inches; C–D, 14 inches; D–E, 8 inches]
As time went on we found on the island two other Philanthus colonies,
although that is rather too large a word to apply to them, since one
consisted of four nests and the other of only two. When we came to
excavate the nests of this species we were greatly astonished at the
length of the gallery, and not until then did we properly appreciate
the industry of these little wasps. It is no small undertaking to
follow one of their tunnels for twenty–two inches, even when, as in
this case, the greater part of it is parallel to the surface of the
ground. We did not find distinct pockets, as the soil was very crumbly
and fell in as we worked, but we came upon clumps of bees an inch or so
to one side of the gallery and about three inches apart, with larvæ in
different stages of development. In one nest we found twenty–six bees
in two clumps, some of them half–eaten, and some of them fresh, but
all quite dead. We have no doubt that punctatus completely provisions
one pocket and closes the opening from it into the gallery, before she
starts another, making a series of six or eight independent cells.
The provision for one larva is probably twelve or fourteen bees, the
capture of which, in good weather, would be a fair day’s work.
That the males do not always stay on in their ancestral home is shown
by an observation that we made on the only occasion that we ever saw
this species in our garden. Nothing was stirring at half past three
o’clock in the afternoon, and we had given up work and started for
home, when, in going up an inclined part of the field, we noticed
something in motion within a ragged–edged hole which ran obliquely into
the ground. It seemed strange that a wasp should be beginning its nest
at so late an hour; but a wasp it was, as we could plainly see when we
took an attitude sufficiently humble. It was loosening the earth with
its mandibles, and then pushing it backward with its hind legs and
abdomen. We had scarcely settled down to watching it when a second one
of the same species appeared, and with a good deal of fuss and flutter
began to dig its hole close by. The spot chosen by this second one
proved unsatisfactory, and another beginning was made in a new place.
Again something was wrong, nor was a third choice any better. At last,
however, the work was started in earnest, and might have been carried
to a conclusion if we had not caught the little creature to satisfy a
suspicion that had been growing in our minds. Yes, we were right. The
worker was not a female making a nest for the rearing of her young, but
a male punctatus, preparing a shelter for the night.
In the mean time the first wasp had pushed back such a quantity of
earth that the hole was entirely closed, but every few minutes he came
backing out to clear the way. At the end of half an hour all became
quiet. The door remained closed, and doubtless the wasp was fast
asleep. Putting a blade of grass and then an inverted tumbler over the
nest, we left him for the night.
On removing the glass at half past seven the next morning, we found
the nest open but the wasp not visible. At half past eight the head
appeared just inside the hole, the long antennæ twitching now to this
side, now to that, as if an inspection were being made. Soon the head
came out. The wasp stood for some minutes making a survey, looking
to right and left with lively jerks of the body. Then, apparently
concluding that the day was not far enough advanced, he came out,
whirled around, and ran head–first into the nest. He probably took
another nap, for all was quiet until just before ten o’clock, when the
antennæ appeared again. The survey was taken as before, first from
within and then with the head in view. At last he flew out, and making
three circles, each one wider than the last, about the place, flew
away. He stayed out all day, and had not returned at half past three in
the afternoon; but on going down at half past four we found that he had
gone in and closed the door from below.
It is clear, then, that these males do not construct a new lodging
every night, but return to the same spot to sleep. Other wasps creep
into crevices. We have often found them, in the morning, in the holes
of the posts of our cottage porch; but we are glad to be able to put
it down to the credit of one male that he has sufficient foresight and
industry to provide a sleeping–place, and sufficient intelligence to
return to the spot when the declining sun warns him that evening is
approaching.
While punctatus was in the height of its activity we found another
species, P. ventilabris, taking bees of several genera and species
into a ground nest. She also carried her prey with her second pair of
legs, and whenever she left her nest she closed the door. She was a shy
little thing, and did not approve of our interest in her. At one time,
being startled by some movement on our part, she dropped her load and
flew away. We placed the bee upon the closed nest, and when she came
back with another, she paused and looked at it, took in the one she
was carrying, and then returned for number one. This was placed on the
threshold while she entered and turned around, and was then pulled in.
Some wasps, notably C. ornata and our little tornado, refuse to take
in their prey, even if they have caught it themselves, excepting in a
regular succession of events; and thus the more reasonable conduct of
ventilabris gains in interest.
To the west of Milwaukee, across the valley of the Menominee, rises
a sandy hilltop which is a little insect kingdom by itself. Ants of
course abound, and the gentle little solitary bees, with their loads
of pollen, may be seen everywhere, seeming to melt into the ground, so
quickly and quietly do they open their burrows. Here Oxybelus plys her
trade of fly–catching, and graceful Ammophila dances with her shadow
over the sunny ground, while Cerceris rests in her doorway with an air
of leisurely superiority to the vulgar cares of life; and here, one day
in early July, a sudden access of energy seemed to strike Aphilanthops
frigidus, a wasp which we had found a year before taking in the
wingless queens of ants. All at once they were digging everywhere,
biting and scratching with great energy, and soon disappearing in
the depths of their sandy tunnels. So deep is their primary gallery
that even in this easy medium it takes them the best part of a day to
get it ready for storing; but once finished it doubtless serves as a
home through the season. It has at the entrance a little cup–shaped
vestibule where the wasp drops the ant as she enters, running out of
sight herself, and then, after she has turned around, coming back to
pull it within. This nest is a very difficult one to excavate neatly,
as the sand falls at the slightest touch.
A day or two after we had seen frigidus making her residential
arrangements, we found twenty–five or thirty within a few feet of each
other, working with great ardor at carrying in queens, the doors being
left closed or open according to individual judgment. The steadiest
workers brought one every forty minutes, scarcely pausing inside the
nest, but others made long stays within, leaving the door closed. The
ants were carried under the body with all the legs folded around them,
but they were heavy things, and were often dropped as the wasp flew
across the field, giving opportunities for robbery that were promptly
taken advantage of. We picked up one of these ants and placed it in
the doorway of a wasp that had just gone in. She came up twice, looked
at it, and backed down again; but the third time she first touched
it, then seized it and took it below. From another wasp that was just
entering we took the ant she had dropped and moved it half an inch
away. When she had turned and come up for it, she seemed surprised,
came out and looked about, found it and dropped it in the doorway,
going in herself to turn around as before. We seized this chance to
move it again, and again she came out, found it, took it back, and
dropped it. This was repeated five times, but when she took it in for
the sixth time, after dropping it, she whirled around and picked it up
so quickly that our malice was foiled.
[Illustration: APHILANTHOPS GATHERING ANTS]
We were puzzled by the actions of a wasp that approached her nest
again and again, but always circled away without entering, until
looking closely we saw that she was pursued by two tiny flies. When she
alighted and walked about awhile with her ant tucked under the third
leg on one side, the flies alighted also and walked about behind her.
In the end she evaded them by a sudden drop into her hole.
A wasp now came circling along with an ant in her grasp, and settled
down between two small weeds that grew about four inches apart. She
stood quiet a moment and then began to dig, but had evidently struck
the wrong spot, for after a moment she moved and tried another place.
Not finding the entrance, she rose and flew close under one of the
plants and began to scratch again, but still in vain. For ten minutes
she persisted, keeping within a few inches of the spot, and holding on
to the ant all the time, although it was dreadfully in her way as she
walked about. Then she dropped it and began to dig more vigorously,
dividing her attention between the two spots she had attempted at
first. She seemed troubled at having to leave the ant, and often picked
it up and tried to hold it while she worked. Once in a while she would
take it with her, and after circling about the spot would disappear,
but in a few minutes she would return. It seemed to us that two little
plants growing near together must have been her landmarks, and that
probably she had been deceived by the likeness that those before us
bore to the ones near her nest. Again and again she seemed to hesitate
and think the matter over, but gradually one of the holes absorbed her
more and more. At the end of an hour she was out of sight in it, and
had carried her ant down, although she was still kicking out sand. It
was evident that her memory had played her false, and that she had
either covered her hole so neatly that she could not find the spot
herself, or had missed the place entirely. She had accommodated herself
to circumstances pretty well, although she ought to have realized
earlier that it would be easier to dig one nest than two.
We now tried to excavate a nest, but could not follow the tunnel,
although we found clumps of ants at different levels, some with larvæ
feeding on them. The deepest were eighteen inches down. Hoping to
secure a guide, we borrowed an ant as it was dropped in the doorway
and tied a thread to it. The wasp pulled it in and took it part way
down with this attachment; but before any great depth was reached, the
thread was seemingly bitten off, as we found the free end without the
ant. A second attempt brought no better results.
So long as we were quiet the wasps did not notice us, but after
being disturbed they became shy and circled about a good deal before
entering. Some of the ants were completely paralyzed, while others
moved their abdomens, legs, and mouth parts. All through the morning,
the whole place was in a bustle, but when we came back, after eating
our luncheon in a shady spot, quiet reigned; the colony seemed asleep,
and although we waited for an hour not a wasp showed herself.
The ants that these wasps were bringing all had wings. The European
genus Fertonius takes worker ants which can be picked up anywhere; but
so far as we know, these queens leave the nest only at the time of
their nuptial flight, after which the wings are lost. How then are
they captured? Can it be that the wasps, though not much larger than
their prey, descend into the home of the ants, bearding the lions in
their den, and carrying off their young queens by force of arms? This
smacks of heroism.
Much interested in the matter, we carefully examined the ant–hills
of the neighborhood. Those on top of the hill had openings too small
to admit frigidus, supposing she had wanted to enter, but down on
the roadside below we found some larger doorways and sat down beside
them. We had scarcely arrived when a frigidus appeared on the scene,
alighting six feet away. That she should have come hunting so soon
seemed almost too good to be true, but she certainly was not doing
anything else. She did not dig, nor feed on the clover, nor circle
about as though looking for her nest, but began to clean and brush
herself assiduously. Then she climbed a tall grass blade, and swinging
at the top went through some curious gymnastic performances. Then she
brushed herself again, drawing her third legs over the sides of her
abdomen. This went on from moment to moment, until half an hour had
passed, and more than once the painful suspicion crossed our minds that
this was some trifling male putting in the hours between breakfast
and luncheon. One encouraging fact cheered us: aimless as the wasp
appeared she was slowly drawing nearer and nearer to the nest; and at
last, alighting on the top of a weed close by, she crouched there in
a most peculiar attitude, and gazed intently at the opening. Absorbed
and tense, she looked about to leap upon her prey; but after a time
she relaxed and moved about a little. Presently she came close to
the entrance and seemed on the point of going in; but the ants were
swarming up and down, and we thought that perhaps that step required
more courage than she possessed. At any rate, she did not enter, but
hung about for some minutes and then flew away.
Was this a young wasp out on her first hunt? What strange antiphonal
desires must have stirred at the sight of the nest, and how mysterious
was the power that drew her to it! Was there in her brain any image
of the queen she must seek and sting and carry away from among her
guards and subjects? Or had she perhaps already achieved the adventure,
and did the memory of the bitter nips that little ant jaws can give
make it a harder task than it was the first time, when she risked
the ills she knew not of? That she hesitated and carried on the work
reluctantly seemed to show that her flesh was weak and needed the prick
of conscience to drive it on. Had we here then the small beginnings
of moral sense and perception of duty? Can it be that of such humble
origin is the power that “doth preserve the stars from wrong”?
We went on with these meditations for several days while lingering,
with gradually diminishing hopefulness, over one ant–hill after
another. The wasps were carrying in winged queens by the score, but
they did not come our way to find them; and although we ranged about
widely, we failed to see the capture. Occasionally we met a frigidus
hunting, running about on the ground and poking her head, not only into
ant holes, but into holes of all sorts, and as we sometimes saw young
queens (wingless however) starting to dig their nests, we thought these
might be the object of the search. The weather was cold and windy, most
unpropitious for swarming, and yet frigidus was working as briskly as
ever; so that we began to feel sure that she could not depend upon
meeting the queens outside the nest, but must enter to get them. Just
as this point we received a letter from Mr. William M. Wheeler, well
known as an authority on ants, saying that he felt very sure that the
wasp could not extract the queens from the nest, but must find them
running on the ground, just after the nuptial flight, before they dug
their holes and started their colonies. Respecting this opinion, but
still feeling unconvinced, we caught a wasp in a glass, and carrying
it to an ant–hill, inverted it so that she was confined just over
the entrance. After buzzing up and down for a moment, she alighted
and walked calmly into the hole; but a fraction of a second later
she came rushing madly out again, pursued by the most furious lot of
ants that ever defended the home city against invasion. Down tumbled
our air castles about courage and duty, for however frigidus gets her
queens, it is not in that way. We have not yet seen the meeting and the
capture, but hope that sometime we may be lucky enough to be on the
right spot at the right time.