A 1893 note from Science by H. Garman on silk-spinning fly larvae (Diptera), including cave-dwelling Mycetophilid larvae from Kentucky caves and Simulium larvae in streams. He argues that their threads count as silk in a biological sense, produced by special glands and used like the silkworm's product, even if not chemically identical to commercial silk. The article describes web-building behavior, the slime coating on the larvae, the pupa, and a letter from H. G. Hubbard on a similar Jamaican cave larva. Four line figures show larvae, a web and a pupa.