486 



7. Small species, 1.5 mm.-l.75 mm 4. flavellus. 



— Larger species, 3-3.5 mm 5. confnsiis. 



8. Scape of antennae black, base of flagellum yellow, the remainder pale 



brown ; thoracic vittae, low^er half of pleura?, the seutellum, and 

 postnotum greenish black, contrasting strikingly with the w^hitish 

 green abdomen 6. piisio. 



— Scape of antenna yellow ; thoracic vittae pale ferruginous or indis- 



tinguishable ; thorax and abdomen yellow or greenish yellow 



7. tenuis. 



9. Thorax entirely black, wholly or partly glossy; legs entirely pale 



yellow ! ". ' .' ! ... 10 



— Thorax yellow or greenish, the spaces between the yitta? always 



noticeably paler than the yittae ; or legs brownish 12 



10. Small species, 2.5-3 mm. in length; abdomen pale green; basal 



joint of fore tarsi more than one half longer than fore tibia; 

 hypopygium as in Figure 8, Plate XXXYI 8. viridiventris. 



— Larger species, more than 4 mm. in length ; abdomen black, with or 



without pale posterior margins to the segments; basal joint of fore 

 tarsi less than a fourth longer than fore tibia 11 



11. Abdomen usually with yellow posterior margins to the segments; 



apical portion of lateral arm of hypopygium black or blackish 

 brown and not as long as basal portion 9. ohediens. 



— Abdomen entirely black except the apical portion of lateral arm of 



hypopygium, which is yellow and noticeably longer than basal por- 

 tion 10. ffavicaiida. 



12. Basal joint of fore tarsi less than one half longer than fore tibia. . . 



lo 



— Basal joint of fore tarsi more than one half longer than fore tibia 



15 



13. Basal joint of fore tarsi nearly one half longer than fore tibia 



(48 : 33) .' 11. 2)oUtus. 



— Basal joint of fore tarsi at most one fourth longer than fore tibia 



14 



14. Thorax yellowish, yitta brown ; abdomen green ; proportions of fore 



tibia and basal joint of fore tarsi, 20 : 25 12. muticus. 



— Thorax brown, yitta glossy black ; abdomen black ; proportions of 



fore tibia and basal joint of fore tarsi, 35 : 42 13. similatiis. 



15. Small species, averaging 2 mm. in length; distance from base of 



first vein to cross vein about half as long as distance from cross 

 vein to apex of wing (20 : 41) 14. exigmis. 



— Larger species, averaging 3 mm. ; distance from base of first vein to 



cross vein distinctly more than half as long as distance from 

 cross vein to apex (35 : 50) 15. duhius. 



16. Thorax and abdomen black 17 



— Thorax and abdomen yellow or greenish, the former sometimes with 



dark vitta ." 20 



