128 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



its base, this joint and the third are both slender at base, gradually en- 

 larged, pulvillate beneath, apically truncate. The antennae are quite 

 long, the stem portions of the joints being longer than usual. The last 

 joint reaches as far back as the scutellum. The length of the praescutum 

 and scutellum about equals that of the postlumbium and postscutellum. 



Female: Cephalothorax about 0.2 mm. long, golden yellow, not much 

 darker behind the opening of the brood canal; almost one quarter longer 

 than wide; sides constricted at base, parallel at middle, angulate and 

 convergent from anterior third, sinuate at apex. Mandibles large, obtuse 

 with outer edges marginal; front convex extending beyond mandibles and 

 separating them by a little more than their width. Opening of brood 

 canal broad, trapezoidal. Spiracles ventral, close to margin. 



Type, four paratype males, and allotype female in U. S. Nat. 

 Mus., Cat. No. 18813. 



SUBFAMILY HALICTOPHAGINAE. 

 PYRILLOXENOS new genus. 



Male: Head not conspicuously excavated behind. Eyes large, convex 

 with very large facets. Mandibles short, triangular, glabrous. Antenna? 

 short, seven-jointed, flattened foliaceous, with large sensory pits; first 

 two joints simple, the second shorter; the remaining five joints crowded, 

 each broadened laterally in a broad lamina, the apices of which are about 

 even with each other, the entire antennae not longer than width of head. 



Pronotum very short, transverse bandlike. Mesonotum a little longer, 

 also bandlike. Elytra pedunculate, spatulate, sensitive, pubescent. 

 Metanotum with prsescutum rounded, keystone-shape, truncate, sinuate 

 at apex, longer than scutellum and postlumbium together; scuti oblique, 

 considerably surpassing prsescutum at outer angles and supporting it by 

 a tiny projection at inner angles; scutellum broad, irregular in outline, 

 narrower at base than praescutum, broadening in a concave line behind scuti, 

 with anterior angles rounded, almost rectangular, and posterior angles 

 diagonally produced as quadrate peduncles, apex otherwise truncate; 

 postlumbium short, transverse, fitting in between and scarcely surpassing 

 the posterior peduncles of the scutellum; postscutellum large, convex, 

 broadly rounded. 



Tarsi three-jointed, the first joint mucronate; claws absent. Eighth 

 ventral segment acutely produced beneath ninth. Anal segment small, 

 flaplike. CEdeagus strongly bent, broad near base, rectangularly bent near 

 apex, apical process slender and very acute. 



The generic name is derived from Pyrilla (the host genus) + 

 Xenos (the typical Strepsipterous genus), signifying a Strepsip- 

 terous parasite of Pyrilla. 



Type of genus, compactus n. sp. 



