49 



their life histories vary to such an extent that it does not seem wise to 

 give a detailed description of them in this brief talk. The grower who 

 wishes to get detailed information on these pests should refer to West 

 Virginia Bulletin No. 128 and U. S. Department of Agriculture Bul- 

 letin No. 1066. There is a fly maggot that injures black and Persian 

 walnuts known as the Walnut Husk Maggot (Rhagoletis suavis Loew), 

 that has been doing considerable damage to Persian walnuts in this 

 state, which seems deserving of special mention. 



Walnut Husk Maggot 

 The maggots attack ripening black and Persian walnuts doing a 

 three-fold injury. In the case of Persian walnuts the eggs are deposited 

 in the husks at a sufficiently early date to prevent the development 

 of some of the nuts. In addition, the black juices that surround the 

 area of infestation stain the shells so that the nuts are not desirable 

 from a marketing standpoint. In addition, the feeding of the maggots 

 renders it difficult and disagreeable to remove the husk from the nut. 

 In black walnuts the ovi-position takes place at a later date, therefore 

 the nuts mature but the feeding of the maggots makes it impossible 

 to get the nuts thoroughly clean of the outer husk. This, however, 

 can be overcome by the present method of polishing black walnuts. 



The adult insect that causes this injury is a fly about one-third inch 

 in length, pale yellow in color, marked with dark brown. The female 

 lays eggs in punctures in the husks and the maggots which hatch from 

 the eggs feed beneath the husk. The maggots are about one-half inch 

 in length. They pupate in the soil in the fall and the adults emerge 

 the following summer, beginning about the middle of July. 



The first evidence of injury is likely to be a small blackened punc- 

 ture from which there exudes a gummy liquid which runs down the side 

 of the r>ut and stains it black. When large numbers of maggots are 

 working beneath the husk the whole nut has a blackened appearance. 

 These nuts fall to the ground prematurely. 



Experiments by the Department of Agriculture indicate that a 

 spray early in August with arsenate of lead, either sweetened or un- 

 sweetened, will destroy a large percentage of the adults before they 

 have a chance to oviposit. This is the same system as used against the 

 apple maggot in the north. It has been found that sweetening the 



