February, '17] COOLEY: SPINACH CARRION BEETLE 101 



are sometimes seriously injured. Chittenden (Bulletin 43, Bureau of 

 Entomology, 1903) has recorded the sugar beet as being fed upon. 



In Montana, we have found the insect feeding injuriously only on 

 the sugar beet and have found both adults and larvae feeding abund- 

 antly on Monolepis nuttalliana and Solanuni trifloruni and adults only 

 on alfalfa. We have also seen the larvse feeding in considerable num- . 

 bers on young wheat. The three weeds mentioned should be looked 

 upon as the normal food plants of this insect and the seat of the diffi- 

 culty. They are weeds of cultivated fields and do not occur on soil 

 that has never been broken. 



It is not clear whether or not Silpha bituherosa feeds normally also 

 on carrion. In 1910 larvge and adults were placed with carrion in 

 cages and as controls other species of the genus known to feed on 

 carrion were placed in other cages under like conditions. Silpha bitu- 

 herosa fed very sparingly, if at all. It was not seen in the act of eating 

 while the other species ate freely. The larvse have been seen to eat 

 living pupae of the same species and on one occasion one larva out of 

 a lot that had not been given sufficient vegetable food was seen to be 

 eating on the tail of a dead mouse. 



To the writer, who has been observing the species for several years, 

 it seems clear that both larvse and adults feed normally on a wide 

 variety of green vegetable foods and seldom, if ever, feed on carrion, 

 as do other members of the genus Silpha. On one occasion when 

 larvae and adults were found to be abundant and destructive in a 

 rather closely localized region in a field of young beets, an attempt was 

 made to find carrion in the locality, but none could be found and the 

 farmer stated that he did not know of any in the neighborhood. 



Remedies 



From the fact that the insects commonly migrate into beet fields 

 from weedy places near by, it is plainly indicated to be desirable to 

 practice clean farming, keeping the vicinity of beet fields as free of 

 weeds as possible. 



At the time the larvse and adults of this insect are injurious to beets 

 the plants are generally quite small. Sometimes the mere seedlings 

 are attacked. It is not feasible, then, to destroy the insects by poison- 

 ing the beet plants, unless, as is sometimes the case, the plants have 

 become large enough to have a considerable expanse of foliage when 

 some arsenical could probably be used effectively. 



One writer has recommended that seeds of Monolepis nuttalliana 

 be sown as a trap crop on which to poison the insects. The writer is 

 not certain that this would be effective. It is feared that the insects 

 could not be destroyed by spraying with an arsenical with sufficient 



