400 DIPTERA. 



traction behind the middle of the head ; its surface is rough- 



o 



eued with transverse wrinkles, but no regularly marked sutures, 

 indicating the divisions between the segments, are apparent. 

 It has been introduced from Europe, according to Mr. Sauborn, 

 by the importers of Dutch bulbs. 



The well known genus Syrphus (Fig 320, S. politus Say) so 

 useful in reducing the immense numbers of plant-lice, lays a 

 single egg in a group of plant-lice, which hatches out a footless, 

 eyeless, flattened, transversely wrinkled, gaily colored green and 

 purple maggot (Fig. 321) having a very extensile body, which 

 enables it to reach up and grasp the Aphis by the peculiar 

 sucking mouth-parts. When fully grown the larva adheres by 

 means of a glutinous secretion to a leaf, its body contracts and 

 hardens, forming a half cj-lindrical puparium. 



The species of Yolucdla are parasitic in their habits, the 

 larvae feeding on those of Bombus. They are long, "narrowed 

 in front, transversely wrinkled, with flue lateral points, and the 

 tail is armed with six radiating points ; the mouth is armed 

 with two bifid mandibles, and three pairs of tentacula." 

 (Westwood.) The pupae are not known. The fry would be 

 easily mistaken for a bee, nearly attaining the size of the 

 worker Humble-bee, being remarkably plump and hirsute. J. 

 Iviinckel states that in Europe two species are known to live 

 in the nests of Vespa. 



XE Leach. The species of this family bear some 

 resemblance to the wasp, Eumenes, from their long, slen- 

 der, pedicelled abdomen. The three basal cells of the wings 

 are large, the third closed, more or less remote from the pos- 

 terior border, and all the longitudinal veins are simple. The 

 eyes in both sexes are smaller than in the preceding family, 

 being separated. The proboscis is, with a few exceptions, 

 much prolonged, and the third joint of the antennas has either 

 an apical style or a thick dorsal bristle. The male genital 

 armor is symmetrical and turned beneath the abdomen. The 

 flask-shaped larva of Conops is " soft, whitish, eleven-jointed, 

 with a long neck and a mouth armed with lips and hooks (man- 

 dibles), and two lateral elevated plates supporting the two 

 spiracles." It was found by Lachat and Audouin living in the 



