CHALCIS (kal'sis) FLIES, or CHALCID IREE, (Neo-Lat. now pl., from Gk. xrdaitc, chalkis, lizard, either from XaXas, (halkis, a city of Eubtea, or, more probably, like the name of the town itself, from xa2.K4c, chalkos, copper). A group of very small Hymenoptera, characterized by elbowed feelers. They number thousands of species, and are truly parasitic, ex cept a few gall-making genera. One large sec tion glues its eggs upon the backs of caterpillars of moths. These eggs hatch in about two days, when the grubs quickly bury their heads in the skin of their host and begin to feed, growing more rapidly than any other known insect-lame, and reaching full growth within three or four days. The first to mature then withdraws its head. preparatory to pupating—an net which at once causes the death of the ex hausted caterpillar and consequently of many belated grubs. The more advanced survivors spin and attach their cocoon to the under side of the empty skin of the dead host, which thns furnishes a roof, and within about eight days complete their transformation and emerge as adult chalceids. The fact that
they attack many fly-maggots, caterpillars. etc.. greatly injurious to cultivated plants, and de stroy them with much speed and certainty, places them among the most valuable aids man kind has in his warfare against insect pests. It is due to these insects, principally, that the •otton-worm of the South is kept down, and millions of dollars' worth of cotton saved each year. "Nowhere in Nature." remarks L. O.
Howard, "is there a more marked example of the en-relation between structure and habits than curs in this family. . . So that it is possible for an experienced person, 011 seeing 2 new spe eies of chaleis fly, to tell precisely what kind of insect it w ill be found parasitic upon." Svc Howard, The Insect Book (New York, 1901) : also papers. often illustrated, by L. O. Howard and Wm. 11. Ashmead, in the publications of the S. Department of Agriculture.