832 



AN INTRODUCTION TO ENTOMOLOGY 



transform. The pupag of the Stratiomyiidse are enclosed within the last 

 larval skin, differing in this respect from other Brachycera (Fig. 1064) . 

 This is a large family ; more than three hundred species, represent- 

 ing more than forty genera, have been described from North America 



Family XYLOAIYIID^ 

 I group together here, provisionally, two genera, as representing 



CH2+2dA 



Fig. 1065. — Wing of Xylomyia. (After Verrall.) 



a separate family, that have been placed by some writers 

 in the Stratiomyiid^ and by others in the Rhagionidce. 

 These genera Q.veXylomyia and Rhachicerus. Both differ 

 from the Rhagionidse, as restricted here, in the form of 

 the antennee, they clearly belong with the Anomalous 

 Brachycera. They differ from the Stratiomyiidae in that 

 the branches of radius are not crowded together near the 

 costal border of the wing and in the possession of tibial 

 spurs. They agree with each other and differ from all 

 other Anomalous Brachycera found in our fauna in that 

 cell M3 is closed (Fig. 1065). 



Xylomia. — This genus includes rather elongate flies, 

 somewhat Ichnenmon-like in appearance, which are mainly 

 of black coloration with more or less yellow markings. 

 The fiagellum of the antennae consists of eight closely con- 

 solidated segments, the last of which usually bears a tiny 

 style (Fig. 1066). Six species have been described from 



our fauna. ■t'lg- lobb.-- 



The larvae of Xylo- ^lyZ 

 myta palhpes have been m y i a . 

 found under the bark of (After 

 fallen trees and are pre- Verrall.) 

 dacious. 



Rhachicerus. — The members of 

 this genus resemble Xylomyia in the 

 form of the body but differ mark- 

 edly in the structure of the antennee. 

 In Rhachicerus the fiagellum of the 

 antennas consists of from twenty to thirty-five segments. The seg- 

 ments of the fiagellum are more or less cup-shaped ; and in some species 



Fig. 1067. — Antenna of Rhachicerus 

 (From Williston.) 



