AN ANNOTATED BIBLIOGRAPHY ON APHELINUS MALI (HALD.), 
A PARASITE OF THE WOOLLY APPLE APHID 
1851-1950 
/ Compiled by 
M. A. Yothers,— Division of Fruit Insect Investigations 
The woolly apple aphid ( Eriosoma lanigerum (Hausm.)) is one of the 
most important enemies of the apple. It attacks the foliage, twigs, fruit, 
roots, and any wounds on the tree. Many control methods have been 
tried, including spraying, dusting, dipping, fumigation, the development 
of resistant rootstocks, and natural control by predators and parasites. 
The hymenopterous parasite Aphelinus mali (Hald.) is a highly effective 
parasite of the woolly apple aphid. Its use for the control of this pest 
has been significant in Oregon and Washington, where it was found to be 
largely responsible for the development of perennial apple canker 
( Gloeosporium perennans (Zeller and Childs)). The introduction and 
establishment of the parasite in these districts reduced both aphid and 
canker to a minimum. 
Aphelinus mali is one of the most effective insect parasites. It is a 
native of North America, having been first described by Haldermann (1) 
in 1851. Since that time, but particularly during the period 1920-40, 
this parasite has been studied and introduced into most of the apple- 
growing regions of the world. In most of them it is giving more or less 
control of the woolly apple aphid, and considerable literature has grown 
up relating to it. This bibliography covers the literature from 1851 
through 1950. 
Most of the references were taken from the Review of Applied Ento- 
mology, Series A. A few were obtained from "A Biological Study of 
Aphelinus mali Hald., a Parasite of the Woolly Apple Aphid, Eriosoma 
lanigerum Hausm." Lundie (70); " Aphelinus mali and Its Travels" 
Howard (129); and from the bibliographies in other articles. 
_l/ Retired June 30, 1949. The compiler acknowledges much helpful 
cooperation from E. J. Newcomer of the Division of Fruit Insect Investi- 
gations, without which the work would not have been completed. 
