THE GRAIN" BUG. 29 



in this instance. In a similar experiment started on August 17, 1915, 

 the duration of the life cycle was 26 days. 



The comparatively short life cycle of T. ashmeadi enables the 

 species to complete several generations each year and greatly in- 

 creases its value as a parasite. 



PARASITES OF THE ADULT. 



Field collections made from various and widely separated localities 

 during 1915 and 1916 demonstrated that in some fields nearly 25 per 

 cent of the adults and last-instar nymphs were parasitized by the 

 tachinid fly GyTrmosoma fuliginosa. 



Pig. 12. — Oymnosoma fuliginosa, a fly parasite of the grain-bug adult. Mucli enlarged. 



According to Morrill (5) the female of this species usually de- 

 posits her eggs near the margin of the body on the ventral pro- 

 thoracic region of the adults and fifth-instar nymphs. The manner 

 in which the resulting larva enters the body of its host has not been 

 observed. The body contents are consumed within a short time and 

 the fully developed parasite larva makes an exit through the anal 

 opening of its host and enters the ground for pupation. The period 

 of pupation for 24 individuals reared during the summer of 1916 

 varied. from 6 to 15 days, the average period being 11.4 days. 



The parasitized insect retains its activity and powers of destruc- 

 tiveness up to within a short time before the parasite is due to 

 emerge. This characteristic detracts somewhat from the value of 

 G. fuliginosa and renders it of less importance than the ^^g parasite 



