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.
Chapter VIII
THE WOOD-BORERS
OUR two species of Trypoxylon are both slender-waisted black wasps, albopilosum having bunches of snowy white hairs on the first legs, and measuring three quarters of an inch in length, while rubrocinctum is a little smaller, and, as the name implies, wears a red girdle.
Although these wasps are called wood-borers, they will use convenient cavities in any material. When we went out to our summer cottage, in the last days of June, 1895, we found many little wasps of the species Trypoxylon rubrocinctum busily working about a brick smoke-house on the place. Closer examination showed that in the mortar between the bricks were many little openings leading back for a considerable distance, which were occupied by the wasps. It would seem that these holes were excavated by some other agency than the wasps themselves, as they were so much too deep for their purposes that before using them they built a mud partition across the opening about an inch from the outside of the wall. Later we found nests of the same species in the posts which support an upper balcony of the cottage; and here, too, the wasps made use of holes which were already excavated.
In the following summer we found large numbers of these wasps at work in a straw-stack. The stack had been cut off perfectly smooth on one side, so that many thousands of the cut ends of the straws were exposed to view, and these proved very attractive to rubrocinctum. This species is very cosmopolitan in its tastes, for we found it utilizing the small holes in the sticks of a woodpile. The straws made the daintiest nesting-places, however, and were well adapted to our purposes, since they could be drawn out of the stack and split lengthwise so that the contents could be easily studied. The two halves could then be brought together again without injuring the inhabitants, and thus we often kept several sets under observation long enough to watch the changes from the egg to the pupa. We found Trypoxylon albopilosum nesting in holes made by beetles in posts and trees, but never in straws. A third species, bidentatum, was very common, nesting in the stems of plants. During the month of August we saw many individuals of this species hunting for spiders on the blackberry bushes; but at this time we were so much absorbed in Crabro stirpicola that we never followed them to their homes.