. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 4 BULLETIN 873, U. S. DEPARTMENT OF AGRICULTURE. in figures 1, b, and 2. The female moth lays eggs in accumula- tions of flour, up and down elevator legs, throughout spouts, around dust collectors, in bolters, purifiers, etc. From these eggs hatch the larvae or worms. When full grown, the larvae are about half an inch long and are whitish or pinkish in color, with minute black dots and fine hairs, as shown in figure 1, c, e. When full grown the larvae spin cocoons in which they transform into the reddish brown pupa? sh
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 4 BULLETIN 873, U. S. DEPARTMENT OF AGRICULTURE. in figures 1, b, and 2. The female moth lays eggs in accumula- tions of flour, up and down elevator legs, throughout spouts, around dust collectors, in bolters, purifiers, etc. From these eggs hatch the larvae or worms. When full grown, the larvae are about half an inch long and are whitish or pinkish in color, with minute black dots and fine hairs, as shown in figure 1, c, e. When full grown the larvae spin cocoons in which they transform into the reddish brown pupa? shown in figure 1. d. From these pup* emerge the parent moths of the next LENGTH OF LIFE FROM EGG TO ADULT. Dean2 states that when the temperature ranges from 85° to 90° F., the eggs of the moth hatch in about 3 days, the larvae become full grown in about 40 days, and the pupal stage requires from 8 to 12 days more. Under ordi- nary flour-mill condi- tions about 9 weeks are required for the pest to pass through its life cycle from egg to adult. Length of the life cycle varies greatly with the tem- perature. At temper- atures lower than 55° F. activity is sus- pended. During most favorable temperature conditions, 24 days has been found by Chittenden3 to be the minimum required for larval development. LARVAL HABITS MAKE MOTH MOST SERIOUS PEST. The Mediterranean flour moth is the most serious of all mill pests, not so much because of the food values it actually consumes, but be- cause the larvae or worms construct in the flour silken tubes in which the}- live, spin a fine silken thread wherever they crawl, and spin co- coons in and about the machinery and stock. As they grow older they spin increasing amounts of silk until, when the)' are full grown, the quantity of web they spin in crawling about machinery, sacks, etc., in search of a suitable place to spin cocoons is enormous, and causes a bad webbing or matting of the flour. These masses of webbed flour receive du
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