PAPERS OX ZOOLOGY 165 



— . Yellow pubescence of the thorax not extending down on the 



pleura to the bases of the legs 3 



2. Fourth dorsal abdominal segment bearing black pubescence 



laboriosus Fabr. 



— . Fourth dorsal abdominal segment bearing yellow pubescence 

 insularis F. Sm. (consultus Frankl.) 



3. First dorsal abdominal segment bearing mostly black pubes- 



cence ; fifth antennal segment longer than the third segment 



variabilis Cress. 



— . First dorsal abdominal segment bearing mostly yellow pubes- 

 cence ; fifth antennal segment no longer than the third 

 segment ash toni Cress. 



Key for the Separation of the Queens of the Genus 



Psithyrus from Illinois. 



1. Occiput of the head bearing mostly black pubescence 



ashtoni Cress. 



— . Occiput of the head bearing mostly yellow pubescence 2 



2. YeUow pubescence of the thorax not extending far below the 



bases of the wings variabilis Cress. 



— . Yellow pubescence of the thorax extending well down on the 



pleura 3 



3. Dorsum of the thorax yellow, except for occasional black hairs 



about the center of the disk ; usually with some yellow be- 

 tween the eyes laboriosus Fabr. 



— . Dorsum of the thorax with more or less of an indistinct band 

 between the bases of the wings, or a large number of black 

 hairs about the disk : usually with a great deal of yellow 

 pubescence on the uper half of the space between the eyes 

 insularis F. Sm. 



BIBLIOGRAPHY 



1802. Latreille, P. A. Histoire natureUe, generale et particuliere des 



Crustaces et des Insectes. Tome 3. Paris. 

 1802. Latreille, P. A. Histoire naturelle des Fourmis. Paris. 

 1805. Panzer. G. W. F. Faunae Insectorum Germanicae. 

 1832. Lepeletier. Ann. Soc. Ent. France. 1. p. 372. 

 1884. Radoszowski, O. Bull. Soc. Imp. Xat. Moscow, Vol. 49. 

 1903. Robertson, C. Synopsis of Megachilidae and Bombinae. Trans. 



Amer. Ent. Soc. Vol. 29. pp. 1T6-1TS. 

 1912. Franklin. H. J. The Bombidae of the New World. Trans. Amer. 



Ent. Soc., Vol. 38. pp. 177-4S6.. Vol. 39. pp. 73-200.. pis. 1-22. 



1914. Morice. F. D.. and Durrant, J. H. The Authorship and First 



Publication of the "Jurinean Genera of Hymenoptera". Trans. 

 Ent. Soc. London, pp. 339-437. 



1915. Sladen, F. W. L. Inquiline Bumble-Bees in British Columbia. 



Can. Ent., Vol. 47, p. 84. 



1916. Prison, T. H. Note on the Habits of Psithi/nis variabilis Cress. 



Bull. Brooklyn Ent. Soc. Vol. 11. pp. 46-47. 



1917. Prison. T. H. Notes on Bombidae. and on the Life History of 



Botnbus auricomus Rott. Ann. Ent. Soc. Amer.. Vol. 10, pp. 277- 

 286. pis. 23. 24. 



1918. Prison, T. H. Additional Notes on the Life History of Bombits 



auricomus Robt. Ann Ent. Soc. Amer., Vol. 11, pp. 43-48. pi. 3. 



