884 



Journal of Agricultural Research 



Vol. VI, No. 23 



Although the fly is prolific and constitutes an effective check to the 

 increase of aphids under favorable conditions, the adults are very frail 

 and easily destroyed by unfavorable weather conditions, such as beating 

 rains. They do not, as a rule, make their appearance in appreciable 

 numbers until the latter part of May and probably can not, therefore, 

 be considered as being so generally reliable as a natural means of con- 

 trol as are the hymenopterous enemies belonging to the subfamily 

 Aphidiinae. 



This cecidomyiid is a general feeder, attacking almost any species of 

 aphid available, but more often feeding on those which live gregariously 

 upon their hosts. The writer's records show that it attacks the following 

 species: Aphis asclepiadis Fitch., A. avenae Fab., A. cardui L., A. gos- 



sypii Glov., A. helianthi Monk, A. 

 maidis Fitch A. setariae Thos., 

 Chaitophorus negundinis Thos., Hya- 

 lopterous pruni Fab., Macrosiphum 

 granarium Kibby, M. pisi, Kalt. M. 

 sonchella Monk, Myzus persicae 

 Sulz., Phorodon humuli Schr., Rhopa- 

 iosiphum sonchi Oestl., Siphi flava 

 Forbes, Siphocoryne pastinacae L., 

 and Toxoptera graminum Rond. 



HISTORICAL SUMMARY 



Aside from systematic discussions, 

 very little has been written about 

 Aphidoletes meridionalis. There can 

 be no doubt that the larvae pre- 

 dacious on Macrosiphum pisi and 

 referred to by Fletcher in his report for 1900 * as a species of Diplosis 

 were Aphidoletes meridionalis, and this seems to be the first authentic 

 record in economic literature. A short account of the habits of prob- 

 ably the same species as the one under discussion is given by Webster 

 and Phillips, 2 who refer to it as an enemy of Myzus persicae and of the 

 spring grain aphis or "green bug" {Toxoptera graminum) and predict that 

 it may possibly become an important factor in the control of T. graminum. 

 The writer 3 has referred to this species as an active enemy of the pea 

 aphis (Macrosiphum pisi) and other writers have barely referred to it as 

 predacious on aphids. 



Fig. i. — Aphidoletes meridionalis: Eggs in situ on 

 leaf of rape; a, egg, greatly enlarged. 



1 Fletcher, J. T. Report of the entomologist and botanist. 1900. In Canada Exp. Farms Rpts. 1900, 

 p. 212. 1901. 



2 Webster, F. M., and Phillips, W. J. The spring grain-aphis or "green bug." U. S. Dept. Agr. Bur. 

 Ent. Bui. no, p. 133. 1912. 



3 Davis, J. J. The pea aphis with relation to forage crops. U. S. Dept. Agr. Bui. 276, p. 54. 1915. 



