A very interesting tribe of insects, so diverse from all other known forms as to constitute an order among themselves, that of the _Strepsiptera_, passes its youth in the bodies of certain wild bees. Mr Kirby's account of his first detection of one of these, though often quoted, is so interesting that I must cite it afresh. "I had previously observed," he remarks, "upon bees something that I took to be a kind of mite (_Acarus_), which appeared to be immovably fixed just at the inosculations of the dorsal segments of the abdomen. At length, finding three or four upon an _Andræna nigroænea_, I determined not to lose the opportunity of taking one off to examine and describe; but what was my astonishment when, upon my attempting to disengage it with a pin, I drew forth from the body of the bee a white fleshy larva, a quarter of an inch in length, the head of which I had mistaken for an acarus (_bee louse_)! After I had examined one specimen, I attempted to extract a second; and the reader may imagine how greatly my astonishment was increased, when, after I had drawn it out but a little way, I saw its skin burst, and a head as black as ink, with large staring eyes and antennæ, consisting of two branches, break forth, and move itself quickly from side to side. It looked like a little imp of darkness just emerged from the infernal regions. My eagerness to set free from its confinement this extraordinary animal may be easily conjectured. Indeed, I was impatient to become better acquainted with so singular a creature. When it was completely disengaged, and I had secured it from making its escape, I set myself to examine it as accurately as possible; and I found, after a careful inquiry, that I had got a nondescript, whose very class seemed dubious." Mr Newman, in an essay of much value,[230] has shewn that the larvæ of this tribe of insects are born alive, that they attach themselves to the abdomens of wild bees, nestling among the hair, and that they are thus introduced into the nest of the bee. Here it is somewhat uncertain how they are sustained at first, for at this time the bee-grubs are not hatched; probably they remain without food for some days, or devour a portion of the pollen and honey stored up. As soon, however, as the bee-grub is hatched, the Stylops-larva undergoes a metamorphosis, sheds its six legs, and becomes a footless maggot; it pierces the soft skin of the bee-grub, and feeds on its juices, till its maturity, as the Ichneumon on the body of the caterpillar.