Dryness of either an insect's habitat or its food has often been reported as inducing diapause. This has been well substantiated in Pectinophora (8, 21, 22) and Loxostege (23). Also, a difference in body moisture between forms of the same species, in diapause and not in diapause, has been recorded in Leptinotarsa (9), Lucilia (11), and Carpocapsa (24), there being less water in the insects in diapause. It is significant, though, that in preparing for diapause Leptinotarsa achieves a reduction in moisture content, even when there is an abundance of water outside, by excretion (4).