SERPHOID AND CHALCIDOID PARASITES OF THE HESSIAN FLY 73 



of folds also distinctly punctate but not quite as strongly so as the middle area : 

 spiracles nearly round ; pleura strongly punctate except the usual smooth area 

 along the dorsal margin. Legs normal, the hind coxae weakly sculptured on 

 outer face. Fore wings reaching to apex of abdomen, about two and one half 

 times as long as broad, bare at base for the length of submarginal vein, closely 

 ciliated on the disk ; marginal cilia very short ; marginal vein very slightly 

 more than half the length of submarginal, distinctly a little longer than the 

 postmarginal ; postmarginal and stigmal veins nearly equal, the former a little 

 the longer ; hind wings with marginal fringe rather short. Abdomen conic 

 ovate, about as long as the head and thorax, as broad or a little broader than 

 thorax, practically smooth, subpetiolate, the petiole very short, ovipositor tip 

 very slightly exserted. The abdomen is somewhat variable in shape, sometimes 

 broader than the thorax and less than twice as broad as long, at other times 

 fully twice as long as broad and about as broad as the thorax. 



Color of head and thorax dark metallic green ; abdomen more or less cupreous 

 with the first tergite metallic green at base and usually with a testaceous trans- 

 verse band at apex ; antennae brownish black with the scape entirely pale 

 testaceous, the pedicel and ring joints usually more or less brownish testaceous ; 

 legs, except coxae, testaceous, the femora frequently brownish ; fore and middle 

 coxae often partly testaceous with the outer face metallic; hind coxae mostly 

 metallic ; fore wing with a fuscous cloud behind the marginal and stigmal veins 

 and extending nearly to the posterior margin. 



Male. — Length 2 to 2.4 mm. Antennae long and slender, nearly as long as the 

 whole insect; scape not reaching beyond the front ocellus, cylindrical at base, 

 the apical half slightly thickened, this enlargement sometimes forming a definite 

 projection on the under side just beyond the middle and covered with small 

 round papillae ; pedicel short, about one and one half times as long as broad ; 

 both ring joints small and transverse ; first flagellar joint very slightly longer 

 than the scape, cylindrical, 6 or 7 times as long as broad ; club not differentiated ; 

 the joints from base to apex of flagellum beginning with the first joint beyond 

 the ring joints having approximately the following proportions : 20, 17, 14, 14, 

 12, 11, 9, 8. 11 ; all the flagellar joints clothed with rather coarse hairs which 

 are a little less than twice as long as the transverse diameter of segments, each 

 joint also with 3 or 4 elongate sensoria toward the apex; apical joint terminat- 

 ing in a small tubercle. Abdomen subelliptical, about as long as thorax, 

 petiolate, the petiole slender and about as long as broad. Head and thorax 

 bluish green, the scutellum usually darker ; abdomen with a pale spot near 

 base ; antennae black with the scape pale testaceous, the pedicel brownish ; legs 

 testaceous, the coxae metallic, and femora varying from brownish testaceous to 

 slightly metallic ; wings hyaline. 



REVIEW OF LITERATURE 



Pteromalus maculipennis was described by Walker in 1836 from 

 specimens collected in grass fields near London, England. It w T as 

 next mentioned by Thomson in 1878, when he described Arthrolytus 

 punctatus from specimens collected in Sweden and cited Pteromalus 

 maculipennis Walker as a probable synonym. Dalla Torre's catalog 

 listed maculipennis Walker in the genus Pteromalus and as doubt- 

 fully the same as Arthrolytus punctatus. Schmiedeknecht did the 

 same. In 1925 Masi recorded the species from Italy and France 

 under the name of Arthrolysis maculipennis. , 11 



In 1897 Ashmead described Holcaeus cecidomyiae from specimens 

 reared by Marchal from the hessian fly in France, and at nearly the 

 same time Marchal published this name without description or com- 

 ment in a list of the parasites of the fly in France. In the United 

 States National Museum collection is a male specimen bearing the 

 name label in Ashmead's handwriting and also a small hand-written 



u Apparently Masi and also Ruschka have confused the generic names Arthrolysis 

 Foerster and Arthrolytus Thomson. The former has as a genotype Pteromalus scao- 

 riculus Nees and is isogenotypic with Picroscytus Thomson. Arthrolytus Thomson is a 

 different genus, having as its genotype Arthrolytus punctatus Thomson, v^hich is a 

 synonym of Arthrolytus maculipennis (Walker). 



