2 BULLETIN 992, U. S. DEPARTMENT OF AGRICULTURE. 



condition of the nuts. It was not until an interest developed in cer- 

 tain places in the East in growing the Persian or English walnut 

 (Juglans regia) commercially that a, demand arose for information 

 regarding this pest. When the Persian walnut trees planted in the 

 East began to fruit, these maggots attacked the nuts and practically 

 ruined very promising crops in several localities. The injury to Per- 

 sian walnuts and the fact that the eastern black walnut, one of the 

 favorite food plants of the species, is becoming of increasing im- 

 portance from the standpoint of nut production, have led to the in- 

 vestigation described herein. The project is not yet completed, but 

 the outstanding features of the life history and habits of the insect 

 are now known. Further studies of the species, particularly along 

 the lines of control, are under way. 



BRIEF DESCRIPTION OF INSECT AND INJURY. 



The adult of the walnut husk-maggot is a two- winged fly about 

 the size of the common house fly. The flies appear on the walnut trees 

 at the time the nuts are approaching maturity and lay clusters of 

 white eggs in punctures made in the husk with their sharp ovipositor 

 (PI. Ill, e) or in breaks which they may find in the husk of the nuts 

 (PL II, b, c, d). Apparently no eggs are deposited in the nuts after 

 they drop. The eggs soon hatch and the resultant maggots rapidly 

 convert the green tissue of the husk into black pulp. After attain- 

 ing full growth the maggots enter the ground and pupate, there 

 being only one generation of the flies annually. 



SYNONYMY. 



The following data covering the synonymy of the species were fur- 

 nished by Mr. B. A. Porter, of the Bureau of Entomology : 



Trypeta suavis Loew, 1862, in Monogr. Dipt. N. Anier., pt. 1, p. 75. 

 Acidia suavis Loew, 1S73, in Monogr. Dipt. N. Anier. pt. 3, p. 235. 

 Rhagoletis suavis (Loew). 1S99, in Coquillett, Jour. N. Y. Ent. Soc, 

 v. 7, p. 260. 



DISTRIBUTION. 



This fty probably occurs pretty generally over the natural ranges 

 of the black walnut and the butternut (Juglans cinerea). In 1862 

 Osten-Sacken 2 gave its distribution as the " Middle States.'' In 

 1902 Babb 3 reared the fly from black walnut at Amherst, Mass. 

 Washburn, 4 in 1905, listed the species among the flies of Minnesota ; 



2 Loew, H. monographs op the diptera of north America (ed. by R. Osten-Sacken), 

 pt. 1, p. 75. Washington, D. C. 1862. 



3 Babb, G. F. note on rhagoletis suavis lw., with a description of the larva 

 and puparium. In Ent. News, v. 13, no. 8, p. 243. 1902. 



4 Washburn, F. L. diptera of Minnesota. . Minn. Agi\ Exp. Sta. Bui. 93, p. 118. 

 1905. 



