SEEPHOID AND CHALCIDOID PARASITES OE THE HESSIAN FLY 39 



DESCRIPTION 



Decatoma amsterdamensis differs from other parasites of the hes- 

 sian fly in having a short and much thickened marginal vein. It is 

 more closely related to the species of Eurytoma than to any of the 

 other parasites, but it is distinguishable at once by the thickened 

 marginal vein which is enveloped in a narrow fuscous cloud, and 

 also by the mostly yellow color of the body. It should be rather 

 easily recognized from the accompanying figure. 



Figure 9. — Decatoma amsterdamensis Girault : A, Adult female ; B, antenna of female ; 

 G, antenna of male. A, X 25. 



Female. — Length 2 to 2.5 mm. Head about twice as broad as long, a little 

 broader than thorax, rugulosely sculptured, the face below antennae medially 

 nearly smooth ; eyes nearlv circular, bare ; ocelli in a low triangle ; postocellar 

 line nearly twice the ocellocular, the latter a little longer than the diameter 

 of an ocellus ; antennal scrobe deep, smooth within, broader below than above, 

 its greatest width about equal to the distance between it and the eye margin ; 

 malar space only a little shorter than the eye height, malar furrow distinct 

 and complete; mandibles each with three teeth, the inner tooth very short; 

 maxillary palpi 4-jointed, the apical joint nearly as long as the other three 

 combined. Antennae 11-jointed, moderately clavate; scape attaining the level 

 of front ocellus, clavate, thickest at base and tapering gradually to apex; 



