At the exact centre of my circle, in place of a cavity, I now found a tiny pile of stones, supported upon a small stick and fragment of leaf, which had been first drawn across the opening.
This was evidently a mere temporary protection of the burrow, I reasoned, while the digger had departed in search of prey, and my surmise was soon proved to be correct, as I observed the wasp, with bobbing abdomen and flipping wings, zigzagging about the vicinity. Presently disappearing beneath a small plantain leaf, she quickly emerged, drawing behind her not a spider, as in the case of her smaller predecessor, but a big green caterpillar, nearly double her own length, and as large around as a slate-pencil—a peculiar, pungent, waspy-scented species of "puss-moth" larva, which is found on the elm, and with which I chanced to be familiar.
The victim being now ready for burial, the wasp sexton proceeded to open the tomb. Seizing one stone after another in her widely opened jaws, they were scattered right and left, when, with apparent ease and prompt despatch, the listless larva was drawn towards the burrow, into whose depths he soon disappeared. Then, after a short and suggestive interval, followed the emergence of the wasp, and the prompt filling in of the requisite earth to level the cavity, much as already described, after which the wasp took wing and disappeared, presumably bent upon a repetition of the performance elsewhere. But she had not simply buried this caterpillar victim, nor was the caterpillar dead, for these wasp cemeteries are, in truth, living tombs, whose apparently dead inmates are simply sleeping, narcotized by the venom of the wasp sting, and thus designed to afford fresh living food for the young wasp grub, into whose voracious care they are committed.
By inserting my knife-blade deep into the soil in the neighborhood of this burrow I readily unearthed the buried caterpillar, and disclosed the ominous egg of the wasp firmly imbedded in its body. The hungry larva which hatches from this egg soon reaches maturity upon the all-sufficient food thus stored, and before many weeks is transformed to the full-fledged, long-waisted wasp like its parent.
The disproportion in the sizes of the predatory wasps and their insect prey is indeed astonishing. The great sand-hornet selects for its most frequent victim the buzzing cicada, or harvest-fly, an insect much larger than itself, and which it carries off to its long sand tunnels by short flights from successive elevated points, such as the limbs of trees and summits of rocks, to which it repeatedly lugs its clumsy prey. In the present instance the contrast between the slight body of the wasp and the plump dimensions of the caterpillar was even more marked, and I determined to ascertain the proportionate weight of victor and victim. Constructing a tiny pair of balances with a dead grass stalk, thread, and two disks of paper, I weighed the wasp, using small square pieces of paper of equal size as my weights. I found that the wasp exactly balanced four of the pieces. Removing the wasp and substituting the caterpillar, I proceeded to add piece after piece of the paper squares until I had reached a total of twenty-eight, or seven times the number required by the wasp, before the scales balanced. Similar experiments with the tiny black wasp and its spider victim showed precisely the same proportion, and the ratio was once increased eight to one in the instance of another species of slender orange-and-black-bodied digger which I subsequently found tugging its caterpillar prey upon my door-step patch.
Protecting the Burrow while Searching for Prey
The peculiar feature of the piling of stones above the completed burrow was not a mere individual accomplishment of my wire-waisted wasp. On several occasions since I have observed the same manœuvre, which is doubtless the regular procedure with this and other species. The smaller orange-spotted wasp just alluded to indicated to me the location of her den by pausing suggestively in front of a tiny cairn. In this instance a small flat stone, considerably larger than the tunnel, had been laid over the opening, and the others piled upon it. On two occasions I have surprised this same species of wasp industriously engaged in the selection of a suitable flat foundation-stone with which to cover her burrow: her widely extended slender jaws enable her to grasp a pebble nearly a third of an inch in width.
In my opening vignette I have indicated two other door-step neighbors which bore my industrious wasps company in their arena of one square yard. To the left, surrounding a grass stem, will be seen an object which is unpleasantly familiar to most country folks—that salivary mass variously known by the libellous names of "snake-spit," "cow-spit," "cuckoo-spit," "toad-spit," and "sheep-spit," or the inelegant though expressive substitute of "gobs." The foam-bath pavilion of the "spume-bearer," with his glittering, bubbly domicile of suds, is certainly familiar to most of my readers; but comparatively few, I find, have cared to investigate the mysterious mass, or to learn the identity of the proprietor of the foamy lavatory.
The common name of "cow-spit," with the implied indignity to our "rural divinity," becomes singularly ludicrous when we observe not only the frequent generous display of the suds samples, thousands upon thousands in a single small meadow, but the further fact that each mass is so exactly landed upon the central stalk of grass or other plant—"spitted" through its centre, as it were. The true expectorator is within, laved in his own home-made suds. If we care to blow or scrape off the bubbles, we readily disclose him—- a green speckled bug, about a third of an inch in length in larger specimens, with prominent black eyes, and blunt, wedge-shaped body.