58 WALTER N. HESS. 



larvae require a soft-bodied animal into which they can pierce 

 their mandibles and inject the poisonous secretion. 



These results, while giving no definite data as to the exact 

 food of these larvae, lead one to conclude that they probably eat 

 any soft-bodied insect larva, mollusca or annelid, that they happen 

 to find in their nocturnal wanderings. Snails are probably one 

 of their chief foods, and though these animals are not supposed 

 to be very abundant, they were found abundantly at night in 

 the damp regions where these larvae live. Cutworm larvae were 

 also abundant. Earthworms, except very small ones, were not 

 eaten until they had been with the larvae for a considerable length 

 of time, while other food was eaten very readily. This would 

 seem to indicate that probably snails and small insect larvae, expe- 

 cially cutworms, are their natural foods. 



Among the larvae of many members of the Lampyridas, as 

 well as among certain other more or less widely separated groups 

 of insects, digestion takes place entirely, or partially, outside of 

 the body. This is accomplished by the digestive juices being 

 exuded from the mouth upon the food which is later eaten by the 

 larvae in a more or less completely digested condition. 



'It is characteristic of most insects that feed in this way to have 



FIG. 9. Photurus pennsylvanica larva, labrum, dorsal view. 



very small heads, so that the mouth is not sufficiently large to 

 take in only very small pieces of food. These insects, like the 

 larvae of the Dytiscida?, are predaceous, feeding on living animal 

 food. The nature of this food is such that it could not be easily 



