I 



in AQUATIC HYMENOPTERA 225 



in search of victims. The larva of the parasite 

 spends its whole life under water and inside the case 

 of a Caddis-worm. Its host is not mortally injured until 

 it has prepared for pupation. Like a healthy Caddis- 

 worm, it makes its case fast and closes it up. Then 

 the Agriotypus larva devours it, and crams the 

 remains into the hinder part of the case. It then 

 proceeds to moor the case by a long band, which it 

 secretes from its own salivary glands, and which is 

 the external indication of an agriotypised Caddis 

 Within the case it spins its cocoon, changes to a 

 pupa about September, and winters before emerging 

 as a winged fly. Klapalck believes that this aquatic 

 Ichneumon is very common. 



