14 PROCEEDINGS OF THE NATIONAL MUSEUM vol.75 



exterior prescutal sclerite, otherwise very similar to this, one or two 

 setae. Anterior and posterior sclerites of the parascutal area fused 

 to a single round, rather large compound sclerite in which the 

 spiracle is lodged, two primary setae posteriorly and a few secondary 

 around the spiracle. Epipleural lobe cone shaped, with a sclerite 

 carrying three or four primary setae on the top and as many 

 secondary ones. Hypopleural sclerite distinct, well chitinized and 

 well colored, two setae. Compound eusternal sclerite distinctly out- 

 lined, color rather dark and sharply contrasting against the light- 

 colored skin of the ventral side of the body, one or two primary setae 

 on each side. Sternellar area (plus a parasternal or "coxal" lobe, 

 particularly distinct in the present larva) with two small sclerites; 

 the outer one circular in outline with two setae, the inner one a 

 mere chitinous grain with one seta; both sclerites rather dark and 

 standing out sharply against the light ventral skin. 



Eighth dbdonvhwl segment. — ^With interior and exterior scuto- 

 scutellar sclerites fused into a single compound plate with three 

 setae on each side ; otherwise not differing much from the preceding 

 segments except in size. 



Ninth ahdomhud segment. — Pygidial shield subrectangular with 

 rounded corners, a thick margin, and a somew^hat elevated corrugated 

 discal part; several moderately long and some short setae in the 

 margin and a few on the disk. 



Tenth abdominal segment. — ^With six large, almost equally sized 

 pear-shaped lobes radiating from anus. 



Habits. — Eating foliage of Solidago ; has been recorded as defoli- 

 ating Artemisia sp in Arizona. Pupates in the ground. 



Literature. — 



Balduk, w. y. 



1029. Ent. News, vol. 40. p. 35. (Life History and Bibliography.) 



TRIRHABDA VIRGATA LeContc 



(U. S. Nat. Mus. ; described from larva in vial marked: "On Solidago. 

 Camp Hill, Penns.vlvania, F. M. Trimble coll.") Not recorded as reared. 



No characters have been found by which the larva of this species 

 can be definitely separated from the larva of T. canadensis. 



In both species the larvae appear to vary somewhat in regard to 

 color, the length and number of the setae, and the distance between 

 the interior and exterior sclerites of prescutum and scuto-scutellum. 

 As, however, the imagines are closely related, occur in the same 

 localities, and feed together with their larvae on the leaves of the 

 same food plant, the probability is that the larval material of both 

 species is mixed in our collections. 



