i84 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. 



