OF WASHINGTON. 105 



7. First segment of abdomen entirely yellow 8 



First segment black at base g 



8. Following segments yellow and ferruginous mirandus Cr. 



Following segments with basal black band, widest on segments 



2 and 3 concinnus Cr. 



9. With yellow spot at side of apex laticinctus Cr. 



With broad yellow or white band at apex 10 



10. Scutellum white, legs marked with black robustus Cr. 



Scutellum yellow, legs rufous rufipes Cr. 



Scutellum black at base u 



ii. Second segment black with lateral yellow spots edwardsiidr. 



Second segment with yellow band at apex rileyi n. sp. 



12. Second, third and fourth segments of abdomen rufous 



^terminates Ashm. 



Second and third segments black, marked with yellow 13 



13. Stigma fuscous, first segment with broad yellow band at apex 



pollinctorius Say 



Stigma yellow, first segment with two yellow spots at apex 



xanthostigma Ashm. 



Mr. Howard read the following paper : 



THE HABITS OF PACHYNEURON. 



BY L. O. HOWARD. 



Pachyneuron is a genus of hymenopterous parasites of the 

 family Ckalcidid&, sub-family Pteromalina , and tribe Sphegi- 

 gastrides. It is composed of small species, all under 3 mm. in 

 length, of metallic colors usually rather dull large heads, 

 flat, oval abdomens, and not very active habit. Six European 

 and six North American species have been described. Three 

 of the six European species were described from captured 

 specimens, and nothing is known of their habits. Of the 

 other three Bouche evidently reared his P. aphidis from some 

 plant-louse ; Ratzeburg says of his P. coccorum : ' ' i 9 from 



* This species is certainly wrongly referred to the genus Metopius. In 

 addition to the fact, noted by Mr. Ashmead, that the facial shield is en 

 tirely wanting, it differs from the genus in venation the areolet being 

 small, triangular and petiolate instead of large and rhomboidal and 

 also in character of thorax and abdomen. The scutellum approaches 

 that of Metopius but is longer and narrower than in any described 

 species known to me. This insect may be referred to the genus Tryphon, 

 with which it agrees in every particular except that the metathoracic 

 spiracles are slightly oval instead of round. 



