32 BULLETIN 891, IT. S. DEPARTMENT OF AGRICULTURE. 



sition on the host. Several beetles were observed with larvae at- 

 tached to their bodies near the base of the head and thorax, and it 

 may be that the parasite normally deposits its larvae on that part 

 of the host. The reason for this belief is that parasitized beetles 

 which have been examined usually have their heads severed at the 

 junction of the thorax. A large number of beetles thus examined 

 also have the contents of the thorax and abdomen devoured by the 

 parasitic larvae. When the parasitic larvae become mature they 

 leave the body of the host and transform to pupae either at or a 

 little below the surface of the soil. 



Sarcophaga (Helicobia) helicis Towns, was reared both from the 

 pupa and adult. It is only about half the size of the former, but 

 is more commonly parasitic on Cotinis nitida, and is known as a 

 parasite on a number of other insects. It is quite common in many 

 localities and is widely distributed. The rearing of this species 

 from the pupa of Cotinis leads to the question as to how the adult 

 parasite oviposits (33, p. 25). Evidently the larvae must be para- 

 sitized, and in order to reach the host the only plausible method is 

 for the parasite to enter the ground and deposit the larvae on the 

 host larvae. Considering the habit of this white grub in making 

 perforations to the surface of the ground, it would be an easy matter 

 for the fly to enter a burrow leading to the abode of the host and 

 parasitize it. 



The ability of the host larva to live for a considerable period 

 after being parasitized, and even to pupate in many instances when 

 pupal cells were found with the parasitic larva, is somewhat re- 

 markable. 



An instance of this is recorded by Mr. H. A. Morgan, Bureau of 

 Entomology, when Sarcophaga {Helicobia) helicis Towns, was reared 

 from grasshoppers, and it was found that the functions of the grass- 

 hopper, including mating and ovipositing, continued normally for a 

 period of 95 days, notwithstanding the fact that it harbored the 

 parasite for that length of time. 



Pupal cells contained as many as six or more parasitic larvae of 

 Sarcophaga helicis, and the contents of the cell were completely 

 devoured. In some instances the last larval skin of the host larva 

 was found in the cell, indicating that the larva was able to trans- 

 form into pupa before succumbing to the attacks of the parasitic 

 larvae. 



In laboratory observations the parasitic larvae after becoming full- 

 grown transform to pupae on the surface of the ground or become 

 attached to the body of the beetles when they emerge from that source, 

 or may even enter below the surface of the ground for some distance. 



The good service which this latter parasite may render is, however, 

 problematical. Reasoning from Morgan's observations on grass- 



