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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 11 
and clothed with short setiform hairs, each arising from a puncture. 
Each elytra bears three distinct costae which are more or less coarsely 
muricate. The female is robustly oblong, the elytra usually being 
widest at the middle. A tuft of ordinary piceous spinules occurs on the 
tip of the first joint of the anterior tarsus; the second joint is unmodified. 
The male differs from the female in that the body is more oval in shape, 
the elytra usually being widest at the base. There is a slight modifica¬ 
tion of the first two segments of the anterior tarsus. The males are 
13-20 mm. in length and about 6.5-10.5 mm. in width, while the 
females are somewhat larger in size, being 14-22 mm. in length and 
7-11 mm. in width. 
In the life-history studies, adults emerged from the pupal stage June 
16 and continued to emerge until July 10, the maximum emergence 
occurring about June 24. Field studies coincide very closely with these 
results. During the early part of June, it was almost impossible to 
find adults in the field. Beginning about June 20, however, adults 
became numerous and most of them were of a bright color and the 
body soft, showing that emergence had just taken place. 
E. tricostata may pass the winter as an adult as well as in the larval 
stage. During March and April of 1916, several adults were found 
hibernating in spherical cells under rocks. The mortality, however, 
is very high, varying from 50 to 95 per cent. The writer has never 
been able to obtain eggs from these overwintering beetles. 
While most of the adults emerged before June 24, mating was not 
observed until July 7, when it became general in many of the cages 
and continued until the middle of September. The first eggs were 
deposited July 10, three days after copulation was noted. Egg laying 
continued until October 12, at which time the beetles became inactive 
and appeared to have entered hibernation. 
Thirty-one mated females, confined in cages containing about one 
inch of soil, deposited a total of 5,464 eggs or an average of 176 eggs 
per female, with extremes of 103 and 262. The largest number of 
eggs deposited by a single female during a period of 24 hours was 51. 
The average period of oviposition for this experiment was 48.8 days, 
the longest being 75 days and the shortest 24 days. An average of 
3.7 eggs were laid on each day. The average number of days on which 
eggs were laid by each female was 23.6, with extremes of 11 and 37 days. 
The average number of eggs laid was 8. 
The proportion of sexes was determined for 1,257 beetles collected 
in the field during the summers of 1916 and 1917 and the males seemed 
to predominate, since only 551 of the beetles collected were females 
while 706 were males. Approximately the same proportion of sexes 
has prevailed in the rearing work. 
