WALNUT HUSK-MAGGOT. 3 



and Banks, 5 in 1912, reared flies from butternuts at Plummers Island, 

 Md. There are specimens in the United States National Museum 

 from West Willow and Allegheny, Pa., and Dr. J. M. Aldrich, of 

 the Museum, has in his personal collection specimens from Blue 

 Ridge Summit, Pa., and La Fayette, Ind. During the present in- 

 vestigation the writer has collected or otherwise obtained specimens 

 from the following localities: Boston, Mass.; Wallingford, Conn.; 

 Lockport, N. Y. ; West Willow and Washington Heights, Pa. ; Co- 

 lumbus, Ohio ; New Windsor, Md. ; Washington, D. C. ; and French 

 Creek and other localities in West Virginia. 



FOOD PLANTS. 



The walnut husk-maggot has been known to attack commonly the 

 husks of the black walnut (Juglans nigra) and the butternut (J. 

 cinerea). The writer has reared adults from the husks of the Persian 

 walnut (/. regia) and Japanese walnut (/. sieboldiana). Of the 

 foregoing hosts the black walnut and Persian walnut are preferred 

 to the others, probably on account of the thicker husks. 



DESCRIPTION OF LIFE STAGES. 



THE EGG. 



The egg (PI. II, &, c, d) is white, banana-shaped, distinctly curved, 

 0.9 to 1 mm. in length by 0.2 mm. in width, one end tapering gradu- 

 ally to a rounded point, the other end tapering more abruptly and 

 ending in a minute but distinct spur or pedicle. The eggs are placed 

 in masses compressed closely together (PL II, 5, c, d) in oviposition 

 punctures extending 2 mm., more or less, beneath the skin of the 

 nuts. The female will oviposit freely in any fresh puncture which 

 she may find in the skin made otherwise than with her ovipositor. 

 Small punctures made experimentally in the husk with a sharp point 

 usually were found promptly by the females and filled with eggs. 

 In some cases such punctures would be packed with eggs and the 

 flies would continue to oviposit on the surface until a small mound 

 of eggs covered the opening in the skin (PL II, d). One artificial 

 puncture in a black walnut was found to contain 186 eggs and several 

 punctures made with the ovipositor were found to hold upwards of 

 60 eggs each. The eggs apparently hatch in from 7 to 10 days. 



Oviposition takes place only in the green part of the husk, but 

 after the maggots hatch and begin to feed the point of attack soon 

 shows as a black spot on the surface (PI. IV, a). This spot increases 

 rapidly in size as the burrows of the maggots penetrate the tissues 



5 Banks, Nathan, the structure of certain dipterous laryjs with particular ref- 

 erence to those, in human foods. U. S. Dept. Agr., Bur. Ent., Tech. Ser. Bui. 22, 

 p. 32. 1912. 



