The Bee- Plies 



Typical Life History of a Bee- Fly 



(SystoBcJms oreas O. S.) 



This species is a Western form and is parasitic in the egg- 

 cases of the so-called Rocky Mountain Locust or Western Grass- 

 hopper. It is unfortunate that the life history of no good repre- 

 sentative of the Eastern species in some one of the other genera 

 which may be supposed to live in the nests of wild bees has been 



worked out. Here is 

 a field for some intel- 

 ligent Eastern worker. 

 The eggs of the pres- 

 ent species have not 

 been observed but the 

 larvae are found in the 

 egg-pods of the grass- 

 hopper or near them 

 and of different sizes 

 during most of the 

 year. The larvae be- 

 gin to transform to 

 the pupa state early 

 in the summer and the pupa pushes itself half-way out of the 

 ground in order to disclose the fly. Flies continue to issue dur- 

 ing the summer. Normally there is but one generation annually 

 but there is a great tendency to retardation and sometimes the 

 larvae remain over unchanged until the second year. The larva 

 is a stout, plump, curved, grub-like 

 looking creature with an opaque 

 whitish color with small dark-brown 

 head. The pupa looks something like 

 the pupa of a Lepidopterous insect 

 but bears many spines on the head 

 and thorax and the dorsal ridges of 

 the abdominal segments also bear rows of spines while othe/ 

 portions of the body carry soft dark hairs. 



Fig. 77. — Systcechus oreas. (After Riley.) 



Fig. 78. — S. oreas, pupa. 

 (After Riley.) 



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