Wasps and hornets are not without their enemies, for their nests are frequently infested by parasitical insects that feed upon their grubs. According to Shipley, "In the tropics some species are attacked by fungi, the hyphæ of which protrude between the segments of the abdomen and give the wasp a very extraordinary appearance."
From the wasps and hornets I next pass to a consideration of a few of the species of bees, omitting, however, anything in reference to the common hive bee (Apis mellifica), of which insect entire volumes have been written.
Hundreds of species of wild bees are now known, and they are to be found in almost every part of the world, and doubtless many species yet remain to be described by the entomologists. Those found have been arranged in the two families Andrenidœ and Apidœ by Kirby, and are subdivided into a number of genera. In the first family all the species are solitary of habit, while in the second both solitary and social species are found. True honey-bees are found wild in this country, and the species most nearly allied to them with us is the common bumblebee (Bombus), of which genus upward of fifty species or more occur in North America. This bee, or rather a queen of this species, hibernates all winter, but early in the spring makes her nest. This may be under any old log or piece of turf or the vacated nest of a field mouse. A dozen eggs or so are laid in a mixture she makes of pollen and honey, and the young appear in series from egg to imago, the period of development being of no great length. From this time on the study of the colony is full of interest, but the sequence of events is not altogether unlike what has been described above for the wasps, the nature of the nest and the fate of the eggs when first deposited being the main difference.
Bumblebees are preyed upon by a variety of parasites, the most curious being a species of Apathus, an insect so closely resembling its host that it requires the eye of an expert to detect the one from the other. Many of us are familiar with the history of the tunnels in posts, planks, and similar places made by that large species known as the Virginian carpenter bee (Xylocopa virginica); and then, too, we have its pretty little ally, the bright pea-green Ceratina dupla, that constructs similar tunnels in such plants as have a pithy center, as reeds and elderberry bushes. These tunnels in either case are intended to hold the cells in which the eggs are deposited and the young reared. The habits of the tailor or leaf-cutting bee are even still more interesting (Megachile centuncularis). They have strong, sharp-cutting jaws, by means of which they cut away bits of leaves to be used in the formation of their cells, the site of the nest being in elder stalks or under planks or in the hollows of certain trees. Their very
