A SYNOPSIS OF THE APHIDIDAE 91 



4. Cornicles and hind tarsi subequal 5 



Cornicles longer than hind tarsi 10 



5. Secondary sensoria on III and IV. Boot species _ middletonii Thomas 



No secondary sensoria. Aerial species 6 



6. Ill longer than VI spur 7 



Ill shorter than or at most equal to VI spur 8 



7. IV and cornicles subequal Jithospermi Wilson 



IV shorter than cornicles. Pulverulent cook! Essig 



8. IV and cornicles subequal. Antennae considerably more than one-half the 



length of the body 9 



IV shorter than cornicles. Antennae at most one-half the length of the body. 



senecio Swain 



9. Cornicles twice as long as cauda and slightly swollen before the tip. 



avenae Fabr. 



Cornicles not twice as long as cauda, cylindrical, and tapering toward tip. 



marutae Oestlund 



10. Cornicles less than twice as long as hind tarsi 11 



Cornicles twice as long as or longer than hind tarsi 21 



11. Secondary sensoria on III and IV. Eoot-infesting species. 



middletonii Thomas 



No secondary sensoria. Aerial species 12 



12. VI spur longer than III 13 



VI spur at most equal to III 16 



13. Ground color, black or dark brown 14 



Ground color, a shade of green 15 



14. VI spur one and one-half to two times as long as III. Apex only of femora 



dusky setariae Thomas 



VI spur but slightly longer than III. Apical one-half of femora dusky. 



medecaginis Koch 



15. Pale green. Cornicles and cauda subequal. Dark, mottled green. Cornicles 



twice as long as cauda or longer avenae Fabr. 



16. VI spur considerably shorter than III 17 



VI spur almost as long as III 18 



17. Cornicles swollen toward tip pseudobrassicae Davis 



Cornicles cylindrical and tapering toward tip ramona Swain 



18. Cornicles but slightly longer than hind tarsi 19 



Cornicles about one and one-half times as long as hind tarsi 20 



19. Dark green. Cornicles at least three times as long as broad at base. 



maidls Fitch 



Pale green. Cornicles at most twice as long as broad at base. 



senecio Swain 



20. Dark green to reddish yellow. On Yucca spp yuccae Cowen 



Black or very dark brown with black dorsal bands and spots. On various 



plants euonomi Fabr. 



21. Cornicles distinctly knobbed at tip frigidae Oestlund 



Cornicles normal 22 



22. VI spur longer than II '. 23 



VI spur at most equal to III 25 



23. Pale green with dusky dorsal abdominal markings calendulicola Monell 



Not colored as above, either not green, or if green with dusky dorsal abdom- 



inal markings 24 



