184 Arthropods as Essential Hosts oj Pathogenic Organisms 
123. An Echinorhynchid, showing the spinose retractile proboscis. 
124. June beetle (Lachnosterna). Larva 
frequently in the proboscis, but they occur also in the thorax and 
abdomen. Infested flies are accidentally swallowed by horses and 
the parasite completes its development to maturity in the stomach of 
its definitive host. 
