As we are briefly running through the Hymenoptera our difficulties seem to increase, for with the next division, the Chalcididæ, we hardly know what to do, or to whom we can turn for assistance in naming these brilliantly spangled green and gold colored flies, whose “name is legion.” The laborers in this field are indeed few, so much so that there is not a “specialist” even at the Natural History Museum, South Kensington. Let us go back to one of those “neglected families” which have received but small attention. One reason for this want of attention is, no doubt, because of the extreme smallness of the members of this family, the largest being not more than one-twentieth of an inch long, whereas the smallest is less than one-eighty-fifth of an inch from head to tail. These insect atoms have been classed among the Chalcididæ by Haliday--the originator of the Mymaridæ--who first noticed them in 1833. Since that date Westwood has placed them among the Proctotrupidæ; and now Ashmead--author of American Proctotripidæ--has decided in favor of Haliday’s arrangement, and in this I fully concur. The fairy flies are, without doubt, among the many wonderful parasitic Hymenoptera, the most admirable in their exquisite structure, as well as in their habits and economy. All the species are egg parasites, and each species has its peculiar taste, selecting with unerring instinct the right kind of egg--generally that of an injurious insect--in which the female lays one of its own eggs, which in due time hatches or develops into an active maggot. This maggot feeds upon the contained fluids, and finds sufficient nutriment to bring it to full size, when it assumes the pupal stage. The fly, being matured, bites out a round piece of the eggshell large enough to allow it to escape. The most noticeable character in the fairy flies is the transverse line across the face a little above the insertion of the antennæ. The wings are devoid of all wing nerves, for the sub-costal is so short and stumpy that the wing looks perfectly free. Both the upper and under surfaces of the wings are covered with minute hairs, and the margins of both wings are surrounded by long hair-like ciliæ.