100 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



for forming pupal cells transformed to the adult condition uniformly 

 in 12 days. Others that were fed over dirt and allowed to pupate in 

 the soil emerged as adults in 23 to 26 days after disappearing into the 

 earth. This would seem to indicate that 11 to 14 days were spent in 

 the earth before actual pupation took place. However, the tempera- 

 ture in the tin cans was higher than that in the soil and this would tend 

 to diminish the pupal period in the cans below normal. Other in- 

 sectary notes which we have indicate a prepupal period of 7 to 9 days, 

 ^t is probably safe to say, therefore, that in the insectary the period 

 in the soil is about 25 days and the pupal period is about 18 days. 



Habits of the Adults 



A few days after emerging the adults are indistinguishable from 

 those that have passed the winter in hibernation and have reproduced. 

 They are ready to eat soon after emerging and in our cages ate freely 

 for a few days and then disappeared into the earth. They came out 

 again from time to time and ate food but gradually spent more and 

 more time in the soil until in the fall they were seldom seen. 



Hibernation 



From the fact that we have traced the adults well into the fall and 

 have found them very early in the spring, as well as from the fact that 

 we have no evidence of the occurrence of larvse or pupse in the fall, 

 we have concluded that this insect hibernates as adults and only as 

 adults. It is quite certain that the adults pass the winter buried in 

 the soil. 



Number of Broods 



The complete life cycle has been accounted for at least three times 

 in the insectary, and no evidence has been found in the field that does 

 not harmonize with the results of insectary studies. The oviposition 

 is long drawn out, as has been shown in a previous paragraph, and 

 this fact readily accounts for the occurrence of larvse during a pro- 

 longed period in the early part of summer. These facts, together 

 with the direct evidence which we have that newly emerged adults 

 disappear into the soil for the season without depositing eggs, make it 

 clear that there is but one brood of Silpha bituherosa, at least, at Boze- 

 man, Montana. 



Food of the Species 



Dr. James Fletcher states that Silpha bituherosa feeds on Cheno- 

 podiaceoj and specifically mentions spinach and beet as host plants. 

 He also records Monolepis nuttalliana (chenopodioides) , Chenopodium 

 album and squash and pumpkin, vines of which the latter two, he says, 



