7O WALTER N. HESS. 



became quiet. The larva soon released and bit the worm again 

 in the same region. This time the worm moved much less. 

 The process was repeated several times, and each time the worm 

 was less disturbed, until at the sixth or seventh bite the earth- 

 worm was not aware of the larva's presence. At about this 

 time another firefly larva bit the worm about an inch away from 

 where the first one was feeding. This part of the earthworm 

 was sensitive, and the worm, though much less active, responded 

 much the same as before. About two minutes later a third 

 larva bit the worm in a still different region, with the result that 

 the worm moved a little but much less than for the other two 

 larvae. Ten minutes from the time that the first larva bit the 

 worm it apparently was perfectly paralyzed, and so far as could 

 be determined it was dead. Several slugs and snails were 

 observed in the process of being killed by these larvae. As the 

 reaction of these snails is similar to that of the earthworm, 

 it is sufficient to state that at first the snail appeared to be 

 slightly injured, for in every instance it contracted. In each 

 case, a few minutes after the larva began feeding, the snail was 

 evidently paralyzed for it no longer moved. One of the largest 

 specimens of earthworms obtainable (about seven inches long) 

 was placed in a jar containing moist filter paper with twelve 

 larvae. Although the worm was left with the larvae for six days, 

 and though they were given no other food there was no evidence 

 of any effort being made to eat it. 



While feeding on its prey, the larva keeps its jaws actively 

 moving back and forth, apparently ejecting digestive juices 

 from its mid-intestine by way of the mandibular canal, and with 

 the two inner teeth on the mandibles it tears the worm to pieces 

 and draws small portions into its mouth. At times the larva 

 would almost bury itself inside the body of its prey, apparently 

 preferring the softer internal tissues to those of the exterior. 

 From an examination of the mouth and intestinal contents of 

 larvae, which were killed while they were feeding, and from careful 

 observation of their feeding habits, it seems evident that a certain 

 amount of digestive juices are exuded through the mandibular 

 canals into the host, when it is first attacked, which serve to 

 paralyze it. It is also probable that a certain amount of the 



