WALNUT HUSK-MAGGOT. 7 



a large percentage of the husks of the nuts were blackened through- 

 out and the surface covered with a gummy exudation from the mag- 

 got injury within. Some of the infested Persian walnuts drop 

 prematurely and others hang to the branches until after the 

 sound nuts have fallen. In nuts that are attacked before maturing 

 the development is arrested and the kernel becomes unfit for use. 

 The injury is thus threefold, in that it impairs the quality of the 

 kernel, causes the husk to stick to the shell in the hulling process, and 

 blackens and soils the shell, making the nuts unattractive for market. 



NATURAL ENEMIES. 



Only one parasite of the husk-maggot has been discovered. This 

 is a hymenopterous species, Aplxaereta auripes Prov., reared from 

 the puparia by Babb ( 6 ) at Amherst, Mass. The writer, on Sep- 

 tember 8, 1920, found a small leaf-bug, determined by W. L. McAtee 

 as a species of Lopidea, with its beak inserted through the skin of a 

 black walnut sucking out the contents of a batch of fresh-laid husk- 

 maggot eggs. An examination of the eggs showed that a number of 

 them had been punctured and emptied by the bug. 



METHODS OF CONTROL. 



Experiments in controling the husk maggot with lead-arsenate 

 sprays were conducted in 1920 in the Persian walnut groves of Mr, 

 N. H. Baile, at New Windsor, Md., and of Mr. J. G. Eush, at West 

 Willow, Pa. Only a single application of the spray was made in each 

 case. The grove of Mr. Baile consists of about a dozen seedling trees 

 of various sizes, some of them about 30 years of age. At the time 

 of the spraying all were bearing heavy crops of nuts. This grove 

 was sprayed by means of a power sprayer on August 10, with 3 

 pounds of lead-arsenate paste to 50 gallons of water. The grove of 

 Mr. Rush consists of 18 trees of named varieties, all of bearing age. 

 The trees were producing heavily at the time the spray was applied. 

 The spraying was done on August 9, using 1^ pounds of lead-arsenate 

 powder to 50 gallons of water. Two trees of. the variety known as 

 Rush, three of Hall, and two of Mayette were sprayed with the lead- 

 arsenate solution to which enough molasses had been added to give 

 the liquid a slightly sweetish taste. For treating the Rush grove a 

 small hand sprayer mounted on a wheelbarrow was used (PI. I). 

 The trees of both groves had borne the previous season, but the crops 

 liad been injured seriously by the attacks of the maggots. 



At the time the groves were sprayed the adults of the maggots 

 were appearing on the trees and a close examination of the nuts in 

 the Rush grove disclosed one batch of freshly laid eggs. After the 

 spraying the Baile grove was not revisited until the nuts were almost 



6 Babb., G. P. op cit. 



