ENTOMOLOGY

362 SANITARY ENTOMOLOGYWith the Indian rat fiea the period was greatly lengthened when themean temperature fell below 65° F., human fiea below 50° F., and theEuropean rat flea below 40° F. In cooler climates the winter is probablypassed in this stag~ but in warmer countries adult activities never cease.Fro. 65.-The dog ilea «(JtenocephaIUlf cani,): a, Egg; h, larva in cocoon; c, pupa; d,adult; 8, mouth parts of same from sidell' antenna; g, labium from below; h, 0, II,much enlarged; a, 6, f. g. more enlarge. (From Howard.) From U. S. Dept.Agr., Bull. 248, fig. s. -The adult fieas often remain in tlle cocoons for weeks and emerge whendisturbed.Life Cycle.-The cycle is completed under favorable conditions inFla. 66.-The human flea, Puler:c irrita1l8: Adult female. Greatly enlarged. (Bishopp.)one to four weeks, but it may extend to one and one-third years inextreme cases.Length of Life of Adult Fleas.-A knowledge of the length of life ofthe adults is of much importance in relation to control measures anddisease dissemination. Under coOl, moist conditions Bacot found thehuman fiea to live 125 days, the European rat flea 95 days, the dog flea