rilE CANADIAN ENTOMOLOGIST. 205 



CLASSIFICATION OF THE HORNTAILS AND SAWFLIES, 

 OR THE SUB-ORDER PHYTOPHAGA. 



BY WILLIAM H. ASHMEAD, ASSISTANT CURATOR, DEPARTMENT OF INSECTS, 



U. S. NATIONAL MUSEUM. 



(Paper No. 3.) 



Family V. — Xyelid^. 



No species seems to be known in this family outside of the European 

 and North American faunas, and very few species are described. The 

 group was first treated as a subfamily by Newman as early as 1834. 



The imagoes appear very early in the year, or in February, March and 

 April, deposit their eggs and then disappear, the consequence being that 

 very few are taken and only a few of the commoner forms are known. 

 With more careful collecting early in the season, however, the probabilities 

 are that many more species will be discovered in our fauna. 



The imagoes of three distinct species of these insects, representing as 

 many genera, have been bred recently from the larvae by Dr. H. G. Dyar, 

 and we are not only indebted to him for the first authentic life-history of 

 a species in this group, but also for the first scientific description of the 

 larva. His recent discovery of a large undescribed species in the rare 

 genus Pleuroneura was most unexpected. 



The known genera seem to fall into two well-marked natural groups, 

 distinguished by differences in both the front and hind wings, and which 

 are here treated as subfamilies. 



Table of Subfamilies. 



Front wings with the intercostal vein separated, not uniting with the 

 subcostal ; hind wings with two complete submarginal cells and one 

 discoidal cell ; ovipositor hardly half the length of the abdo- 

 men Subfamily I., Macroxyelinse. 



Front wings with the intercostal vein uniting with the subcostal ; hind 

 wings with one complete submarginal and one discoidal cell; oviposi- 

 tor as long or longer than the abdomen Subfamily H., Xyelinre. 



Subfamily I. — -Macroxyelin^. 



The imagoes of this group are very much larger than those in the 

 Xye/incE, and are readily distinguished by the distinctly separated inter- 

 costal vein, as in the Lydince, and their much shorter ovipositor, while 

 their larvae seem to be strictly external feeders. 



