420 NATURAL HISTORY OF ARTHROPODS. 



erect. These young larva? issued in large numbers from the burrows 'in which they 

 were hatched, and, placing themselves in an upright position at the entrance, allowed 

 themselves to be blown away by the wind. Here for a time they have not been fol- 

 lowed, but it is probable that they attach themselves by the aid of their ventral hooks 

 to the bodies of large-sized beetles, the Hhizotrogus solstitialis, by which they are 

 carried into the ground when the female enters to deposit her eggs. This is probable 

 from the fact that hundreds of pupae and pupa skins were observed near the fence, 

 protruding from the ground, and kept upright by means of their terminal booklets. 

 On searching below these, in every instance the remains of the larval skins Avere found 

 at the depth of about two inches, and still deeper, were found the remains of the above- 

 mentioned beetles, and in one instance the mature larva? were seen issuing from the 

 abdomen of the beetle. 



In the United States only three species of this family are known, a Hirmoneura 

 and two lihynchocephali, the latter interesting from the fact that the two other known 

 species of the genus, both very closely allied to ours, are inhabitants of the region about 

 the Black Sea only. 



The BOMBYLIID.E will be recognized by their having the three basal cells much 

 prolonged, with usually four posterior cells, and the third joint of the antenna? not 

 annulate. The family is a large one, comprising about fourteen hundred known species, 

 and exceedingly rich in varied forms, scattered over all parts of the world. They 

 are usually clothed with long and delicate hairs, and with the wings often with dark 



markings. Most of them are very swift-flying insects, often hover- 

 ing motionless in the air for a time and then darting away with 

 the rapidity of the wind. They seek sunny places in woodland 

 roads, about blossoms, or on rank vegetation. jBombylius fratel- 

 lus appears in New England often in March long before other 

 insects have become at all abundant. In general the members of 

 FlG ' 5S fr(tieUus' byliUS t^ 8 f amn< y are prettily marked, and in their life histories are often 

 very interesting. In the adult state they are flower-flies, feeding 

 upon the pollen and honey which they extract by the aid of the proboscis, which is 

 often very long. 



Bombylius medius, an English species, lays its eggs near the entrance of the holes 

 of a large species of Andrena, whose larvae and pupae are devoured by the fly. 

 Another species is parasitic upon Colias. JB. major, a European species which also 

 occurs in the Pacific States, is also found in the subterranean nests of Andrena. 

 Other larvae of this family are parasitic upon species of Mef/achile, Oemonus, Calico- 

 doma, Limacodes, Odynerus, Trypoxylon, etc. 



Among the most interesting, biologically, and at the same time exceedingly useful 

 insects are Triodites and Systcechus, a number of species of which occur from the 

 central to the Pacific States. Their larvae are found in the egg-pods of the locust 

 Coloptenus spretus, so destructive throughout the West. " These larvae begin to trans- 

 form themselves into the pupa state early in the summer, and the pupa pushes itself 

 half way out of the gi-ound in order to disclose the fly. These continue to issue during 

 the summer months. As a rule but one year is required for full development. 

 Triodites is first observed as a large, yellowish-white grub, about a half an inch long 

 when extended, it being usually curved so that the head and tail nearly meet. It is 

 usually found in a case of locust eggs which it has devoured, pushing the empty shells 

 aside, and at last occupying the space where were twenty-one to thirty-six eggs. Often 



