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True Bees — Part 7

The wasps of the family Crabronidae are usually larger, but still are rather small insects. They burrow in sand and clay and many of them make their burrows in wood--in palings, posts, stumps and decaying logs. They store in their cells a great variety of insects. Xylocrabro (Crabro) stirpicola was found by the Peckhams to fill its cells with different kinds of flies. Others store spiders and plant lice. The interesting observation was made by the Peckhams on the species just mentioned that it works at night and that "her manners were an agreeable contrast to those of the wasps that we had been watching through the day. The feverish excitement of their ways seemed quite in keeping with the burning heat of noon, while Crabro's slow and gentle movements harmonized perfectly with the long shadows of evening." One specimen was seen to work industriously for forty-two hours, toiling from three in the afternoon on July 27, through that night and the day and night following until nine o'clock on the morning of the 29th. "Surely," say the Peckhams, "she takes the palm for industry, not only from other wasps but from the ant and bee as well." Her burrow was thirty-nine centimeters in length and was made in the stalk of a raspberry or blackberry. The species which belong to the genus Trypoxylon and its close allies as a rule make use of the burrows of other insects. They sometimes store the insects which they collect in the deserted cells of a mud-dauber, and sometimes in the small round holes made by wood-boring beetles in old trees. Many of the species seem to store up plant lice but others capture and paralyze different kinds of spiders. There is a very important wasp which belongs to this group which does not occur in the United States but which I am trying to introduce. This is the Ampulex which preys upon cockroaches. A correspondent in Mauritius, D'Emmerez de Charmoy, of the museum at Port Louis, has promised to send me some of these creatures alive. He states that they enter the houses and prey upon the domestic cockroach. Perkins, quoted by Sharp, says that in West Africa cockroaches are stung by these wasps and placed in confinement in some such spot as a keyhole and in one case one was apparently prevented from afterward escaping by the wasp carrying some heavy nails into the keyhole. Rothney, also quoted by Sharp, says, "I saw two or three of these wasps (A ruficornis) collar a peculiar cockroach by the antennae and lead it off into a crack in the bark, but as the cockroach reappeared smiling each time I don't know what was up."

Numbers of other most interesting forms occur here, but those interested must go to the Peckhams' book and to Ashmead's interesting paper entitled, "The Habits of the Aculeate Hymenoptera," published in Psyche, January to May, 1894, and to the papers referred to by the latter author.

The genus Ammophila contains some of the most interesting forms in this family, and the habits of one or more species have been described in the most interesting way by the Peckhams, by the late William Hamilton Gibson, and Dr. S. W. Williston, and by Mr. Theodore Pergande. These are the insects which use tools. Their burrows are deep in the earth and are carefully concealed by the insertion of a stone, over which dry earth is scraped. When the female returns with a caterpillar, (and she travels unerringly to this concealed burrow for a long distance,) the earth and stone are removed, the caterpillar is carried down into the burrow and the mouth is once more concealed until another caterpillar is brought. The solicitude exhibited by the maternal wasp for fear her burrow may be discovered has been vividly described by all of the authors above mentioned. When the burrow is complete the female wasp has been observed to use a stone as a tamping iron to pack the earth into the mouth of the burrow. This is the tool use referred to. Dr. Williston states that he feared to publish his observation at first, since he might not be believed. Pergande noticed that after the burrow was completed and filled the mother wasp revisited the spot occasionally to satisfy herself that everything was secure against intruders and to make surety doubly sure by placing additional disguising objects over the already disguised burrow mouth.