132 MISC. PUBLICATION 174, U.S. DEPT. OF AGRICULTUKE 



DESCRIPTION 



Pleurotropis benefica is like P. metallicus except in the following 

 particulars : 



Female. — Length 3 mm. Postocellar line not quite twice the ocellocular; 

 temples strongly punctate without a smooth border along the eye margin; 

 fovea on each side of clypeus very small and indistinct ; occiput clothed with 

 rather coarse, curved hairs along its margin, these hairs densest and most 

 conspicuous opposite narrowest part of temples ; antennae weakly clavate ; first 

 flagellar joint about three times as long as thick, second joint distinctly shorter 

 than fifth and distinctly longer than third, the latter subquadrate; fourth 

 flagellar joint subquadrate or a little broader than long, fifth much smaller 

 than the fourth, more or less conical and terminating in a process which is 

 much shorter than the body of the segment ; mesoscutum usually a little less 

 than twice as wide as long, the depressions terminating parapsidal grooves 

 posteriorly shallow and sculptured like rest of mesoscutum ; propodeum entirely 

 impunctate, the median carina and lateral folds strongly developed, the former 

 not double basally but forking at or near the middle of propodeum, the two 

 branches diverging ; mesosternum smooth posteriorly ; abdomen ovate, about 

 as long as head and thorax combined, the petiole about twice as broad as 

 long, broader at base than at apex, opaquely punctate, carinately margined lat- 

 erally above and below and often with a weak median longitudinal carina 

 above ; first tergite beyond the petiole finely reticulately sculptured on the apical 

 one third, bare except at extreme lateral margins ; following tergites hairy, 

 finely reticulated, and dull, except a very narrow apical border on each which 

 is somewhat shining. General color green or bluish green, the face and front 

 somewhat darker and the occiput and more or less of the vertex behind the 

 ocelli dull black; antennae black, the scape slightly metallic; legs'all metallic 

 like the thorax, their tarsi all black or very dark fuscous; abdominal petiole 

 dull black, following segment bright metallic green basally, its apical one third 

 and all the remaining segments dull purplish black ; wings hyaline, venation 

 blackish. 



Male. — Length 2.2 mm. Antennae much longer than that of female, not 

 clavate; the scape slightly thickened, about 4 times as long as broad; pedicel 

 a little longer than broad ; ring joints small and transverse ; first flagellar joint 

 3 to 4 times as long as thick, second 2» to 2% times and the third about twice 

 as long as thick ; fourth either as long as third or a little shorter than third ; 

 fifth more slender and usually longer than preceding joint and terminating in a 

 short spine; all flagellar joints hairy, distinctly sculptured, and without elon- 

 gate sensoria. Abdomen short, the segments beyond the fourth usually retracted 

 and concealed ; petiole a little longer than broad, about as long as hind coxae, 

 without distinct lateral carinae; apex of first segment beyond petiole very 

 weakly sculptured and sculpture of following segments much less dull than in 

 the female ; the lateral margins of tergites form a distinct longitudinal fold on 

 each side of the venter. Color as in the female except that the face is bluish 

 green like the .rest of the head and the abdominal tergites beyond the second 

 are more metallic and not so dull as in the female. 



Redescribed from the 16 specimens forming the type series which 

 were reared from Trachelus tabidus (Fabricius) at Mount Holly 

 Springs and Carlisle, Pa.; 1 specimen reared from the same host in 

 Maryland by the writer, and 3 specimens reared from Cephas pyg- 

 maeus Linnaeus in the vicinity of Cambridge, England, by George 

 Salt. A single specimen reared from the hessian fly was examined 

 but subsequently lost before this description was drawn. 



REVIEW OF LITERATURE 



This insect was first mentioned in 1920, when the present author 

 recorded an apparently undescribed species of Pleurotropis as at- 

 tacking the black grain-stem sawfly, Trachel/us tabidus, in Pennsyl- 

 vania. The following year a description of the species was published 



