1912] Life History of Trogoderma Tarsale 373 
line; this extends from the head, through the thorax and partly 
down the abdomen. The larva bends over and assumes a semi- 
circular position which permits the extrication of the thorax and 
head. The legs are then pulled out of their coverings and 
the light colored larva crawls out of the exuvia. Its new, soft, 
chitinous covering soon hardens and assumes the natural 
yellowish brown color within a few hours. 
C. V. Riley (1883) in an article on the number of moults 
and length of larval life as influenced by food, says, ‘Since 
March 13, 1879, we have kept two larve of that common 
museum pest (Trogoderma tarsale) in a light tin box with an old 
silkworm cocoon. They were half grown when placed in the 
box. On Nov. 8, 1880, there were in the box twenty-eight 
larval skins, all very much of a size, the larve having apparently 
grown but little. The skins were removed and the box closed 
again as tightly as possible. Recently, or after a lapse of two 
years, the box was again opened and we found one of the larve 
dead and shriveled up, but the other was living and apparently 
not changed in appearance. There were fifteen larva skins in 
the box. We cannot tell when the one larva died, but it is 
certain that within a little more than three and one-third years 
two larve shed not less than 43 skins, and that one larva did 
not, during that time, appreciably increase in size. 
‘“We know of no observations which indicate the normal or 
average length of life or number of molts in either Tenebrio or 
Trogoderma, but it is safe to assume from what is known, in 
these respects, of allied species, that in both the instances here 
referred to, but particularly in the case of Trogoderma, develop- 
ment was retarded by insufficient nutrition and that the frequent 
molting and slow growth resulted therefrom and were 
correlated.”’ 
My observations and numerous experiments on the starva- 
tion of T. tarsale do not corroborate Riley’s statement that 
insufficient nutrition of larve in all stages of development show 
that a lack of nutrition retards the frequency of moulting. 
Specimens which ordinarily on favorable diet moulted once in 
two weeks, moulted on the average less than half as frequently 
when deprived of food. 
Summary of Variations in Moulting. 
1. Larve shed their first skin from four to nine days after 
hatching. 
