120 OH AS. T. BRUES. 



11. First and second abdominal segments wholly yellowish ; antennae 22-jointed 



11. canadensis Cress. 

 First segment wholly yellowish, second pale banded.. .12. obscurus Cress. 



12. Frst abdominal segment very long and unusually slender, scarcely dilated at 



tip; antennae 21-jointed 13. texanus Cress. 



Head and thorax dark, abdomen except petiole dark. 



var. nigriventris. 

 First abdominal segment not unusually slender 13. 



13. Abdomen wholly ferruginous, sometimes very slightly iufuscated 14. 



Abdomen in great part black or piceons . . 15. 



14. Ovipositor as long or longer than the abdomen ; antennae 24-25-jointed. 



14. unicolor Cress. 

 Ovipositor a little longer than the abdominal petiole, antennae with more 



than 23 joints 15. erssul us sp. nov. 



Ovipositor very short; antennae 19-26 jointed keenii. 



15. Small species, 2.5 mm. or less, first and second abdominal segments rufous; 



antennae 18-jointed 17. minimus Walsh. 



Larger, over 4 mm., or differently colored 16'. 



16. Ovipositor very short, third and following segments pale behind. 



alternatus Cress. 

 Ovipositor at least about as long as the first abdominal segments 17. 



17. Anterior lobe of thorax with a median longitudinal groove; antennae 24- 



jointed 19. dimidisi I us Cress. 



Anterior lobe of thorax not thus sulcate 18. 



18. Tip of abdomen pale 22. 



Tip of abdomen dark or banded ' 19. 



19. Abdominal petiole black, with a yellow apical band; tip of abdomen piceous. 



20. meabi lis Cress. 

 Petiole rufous or ferruginous 20. 



20. Tip of abdomen banded 21. micarise. 



Tip of abdomen black 21. 



21. Antennae 23-jointed 22. otlowaensis. 



Antennae more than 23-jointed 23. flavocinctus Ashm. 



22. Petiole much dilated apically ; secoud, third and fourth segments ferruginous ; 



antennae 19-jointed 25. bii'kinani sp. nov. 



Petiole but slightly dilated ; third and fourth segments more or less fuscous; 

 antennae 25-jointed 26. gracilis Cress. 



Males. 



Apterous 2. 



Winged 5. 



2. First abdominal segment very long and slender, scarcely dilated apically, con- 



siderably longer than the metathorax • • • -13. texanus Cress. 



First abdominal segment shorter and broader 3. 



3. Head black ; small species 4. - 



Head yellowish brown ; antennae 27-jointed 27. macer Cress. 



4. Abdomen wholly black; antenna 1 20-joiuted iiigrelluw Ashm. 



Abdomen pale banded 17. minimus Walsh. 



