DESCEIPTIONS OF SOME NORTH AMERICAN SAWFLY 

 LARVAE. 



By WlLLTAlVI MiDDLETON, 



0/ the Bureau of Entoniolngii, United States Department of Agriculture. 



INTRODUCTION. 



The following paper, which is a contribution from the Branch of 

 Forest Insects, Bureau of Entomology, describes the larvae of cer- 

 tain sawflies which have been obtained in connection with investiga- 

 tions on insects injurious to forest and shade trees and shrubs. The 

 species here treated belong to eight genera, representing four sub- 

 families, of the Tenthredinidae and one genus {Acordulecem) of 

 the Pterygophoridae. The genera represented are briefly character- 

 ized and keys, separating the larvae described, are included. Some 

 In-ief remarlvs, based on notes made in the rearing work on the life 

 and seasonal histories of the species, are added. 



In the descriptions of the larvae the author has used the termi- 

 nology which he had previously adopted for chalastogastrous 

 larvae.^ This terminology recognizes four transverse dorsal areas 

 denoted by the letters A, B, C, and D and four pleural areas termed 

 preepipleurite. postepipleurite, prehypopleurite, and posthypo- 

 pleurite. The spiracle, spiracular area, and alar area are considered as 

 pertaining to the tergum or to the integument between tergum and 

 pleurum and are treated after the discussion of the transverse tergal 

 areas. The ambulatory appendages of the thorax have been desig- 

 nated by "legs" and those of the abdomen by "uropods" except- 

 ing on the ultimate segment, where they are called " postpedes." These 

 appendages are herein treated following the discussion of the pleural 

 nreas since the}' occur between the pleurum and the sternum. The 

 transverse dorsal areas A, B, C, and D may become subdivided, and 

 when so are denoted by B^, B-, or C% C^ and C^ In order that the 

 position of pigment or external morphological characters may be 

 definitely indicated, the body has been divided into a series of imagi- 

 nary longitudinal regions, placed one below the other on each side of 



' LeConte's Sawfly, An Enemy of Young Pines, Jour. Agri. Research, vol. 20, No. 10, 

 pp. 741-760, and Some Suggested Homologies between Larvae and Adults in Sawflies, 

 Proc. Ent. Soc. Wash., vol. 23, No. 8, pp. 178-192, 1921. 



No. 2442— Proceedings U. S. National Museum, Vol. 61, Art. 21. 



1 



