WOOLLY PEAR APHIS ^ 



By A. C. Baker, Eniomological Assistant, and W. M. Davidson, Scientific Assistant, 

 Deciduous Fruit Insect Investigations, Bureau of Entomology 



INTRODUCTION 



For some years a species of Eriosoma has been known to attack pear 

 roots in California. It has, however, been considered to be the woolly 

 apple aphis, Eriosoma lanigerum Hausmann, since both in habit and in 

 structure the two species somewhat resemble each other. To the species 

 on the pear, which, after careful study, proves to be un described, the 

 name '^Eriosoma pyricola" is herein given, and a brief account of the 

 species is attempted. 



HISTORY OF THE INSECT 



Mr. Frank T. Swett is authority for the statement that the woolly pear 

 aphis has been in California for more than 20 years. Ten years ago he 

 says the species ruined about 2,000 French seedlings in one block, while 

 occasional apple seedlings, planted along with them, made normal 

 growth. Attention has frequently been called to the immunity of apple 

 seedlings planted close to infested pear seedlings in nurseries and orchards. 



During September and October, 1897, Mr. Theodore Pergande received 

 specimens of a species of Eriosoma on pear roots from Prof. F. M. Web- 

 ster, of Wooster, Ohio. Through the kindness of Mr. Pergande we have 

 been able to examine these specimens, and they prove to be identical 

 with our California material. It is quite possible, therefore, that the 

 species may be present in other parts of the country, notably in Oregon. 

 It is noteworthy that the Ohio specimens were taken from roots of pear 

 stock received from France the preceding spring. 



The species occurs over practically all the pear sections of northern and 

 central California, and in some regions is a very destructive pest. To 

 entomologists the extent of its presence has been known only for the last 

 three or four years, but reports from orchardists and field observers indi- 

 cate that it has been parasitic upon pear roots for a much longer period. 



HABITS OF THE INSECT 



The insect works entirely underground. The species that has been 

 found feeding on the aerial portions of Nelis, Easter Beurre, and other 

 pears is the woolly apple aphis, E. lanigerum. The woolly pear aphis 



' What is probably the same species has been treated as a pear pest in California under the name Eriosoma 

 lanigera by Geo. P. Weldon. (The woolly aphis as a pear pest. In Mo. Bui. State Com. Hort. [Cal.], v. 4, 

 no. 9, p. 441-444, fig. 94-95. 1915 ) 



Journal of Agricultural Research, Vol. VI, No. 10 



Dept. of Agriculture, Washington, D. C. June 5, 1916 



ea . K— 33 



(351) 



