APHIDOLETES MERIDIONALIS, AN IMPORTANT DIPTEROUS 

 ENEMY OF APHIDS 



By John J. Davis, 

 Entomological Assistant, Cereal and Forage Insect Investigations, Bureau of Entomology 



INTRODUCTION 



The economic importance of Aphidoletes meridionalis Felt was es- 

 tablished when the larvae of this cecidomyiid fly were first observed 

 by the writer at La Fayette, Ind., on June 29, 1912, destroying large 

 colonies of Aphis setariae and Hyalopterus pruni on plum (Prunus spp.). 

 Subsequent observations in the States of Iowa, Wisconsin, Illinois, 

 Michigan, and Indiana emphasize its value as an efficient agency in the 

 natural control of Aphididae. 



While most of the data reported in this paper were obtained during 

 July and August, 191 2, it was impossible to obtain a specific determina- 

 tion of the species from specimens used in the experiments at that time, 

 but during the past season (191 5) Dr. E. P. Felt has kindly determined 

 it as Aphidoletes meridionalis from living adults reared from larvae col- 

 lected in the same locality and attacking the same kinds of aphids as 

 those used in the experiments of 191 2. Aphidoletes meridionalis was 

 described by Dr. Felt in 1908 from adults reared from larvae predacious 

 on the tulip-tree aphis (Alacrosiphum Hriodendri Monl.). 1 



ECONOMIC IMPORTANCE, NATURAL CHECKS, AND APHIDS ATTACKED 



The fact that each larva may destroy dozens of aphids and that these 

 flies are remarkably prolific makes this predator very important and 

 valuable. Many instances were observed where aphid colonies were 

 apparently completely destroyed. For example, on June 6, 191 5, the 

 undersides of leaves of catnip (Nepeta cataria L.) in the writer's yard were 

 completely covered with Aphis gossypii, and at that time Aphidoletes 

 meridionalis was just making its appearance in numbers, the eggs and 

 larvae up to half or possibly two-thirds grown being abundant. A week 

 later (June 13) very few aphids remained, and most of the predacious 

 larvae had made cocoons on the undersides of leaves between the leaf 

 veins or on the ground at the base of plants, and a few days later only 

 very rarely could a live aphid be found. A few syrphid larvae, an oc- 

 casional coccinellid larva or adult, and some aphidiine parasites were 

 present, but the control of the aphis was apparently due entirely to 

 A phidoletes meridionalis . 



1 Felt, E. P. Studies in Cecidomyiidae II. In 23d Rpt. State Ent. N. Y., 1907, p. 384, 397. 1908. 

 (N. Y. State Mus. Bui. 124). 



Journal of Agricultural Research, Vol. VI, No. 33 



Dept. of Agriculture, Washington, D. C. Sept. 4, 1916 



fh K —42. 



(883) 



