WALNUT HUSK-MAGGOT. 



'Creek, W. Va., the first flies appeared in rearing jars on July 16, 

 and on August 5 the first specimens were recognized definitely on 

 the trees. Flies, apparently of this species, were seen on trees in both 

 West Virginia and Pennsylvania several weeks earlier, but no 

 specimens were captured and identification was not definite. Flies 

 in rearing jars issued from July 16 to September 8, emergence cover- 

 ing a period of 55 days. Table I shows the time of emergence of 40 

 individuals in rearing jars. 



Table I. 



-Emergence of flies of walnut husk-maggot in rearing jars at 

 French Creek, W. Va., in 1920. 



Date 



Num- 

 ber of 

 flies. 



Date. 



Num- 

 ber of 

 flies. 



Date. 



Num- 

 ber of 

 flies. 



Date. 



Num- 

 ber of 

 flies. 



July 16. . . . 

 17.... 

 18. . . . 

 19 



20. . . . 

 21.... 

 22. . . . 

 23.... 

 24.... 



26. . . . 

 27.... 

 28.... 

 29.... 

 30. . . . 



1 





 

 2 

 



1 

 



1 





 



1 





 

 

 



July 31. . . . 



Aug. 1 



2 



3.... 

 4 



6 



7 



8 



9 



10.... 



11.... 



12 



13.... 



14.... 



1 

 1 

 

 

 1 

 



1 

 1 

 1 

 1 





 

 2 

 1 

 



Aug. 15 — 

 16... 

 17... 

 18... 

 19... 

 20... 

 21... 

 22... 

 23... 

 24... 

 25... 

 26... 

 27... 

 28... 



3 

 

 2 

 2 

 3 

 

 

 



1 

 1 



4 

 4 

 1 

 



Aug. 29... 



30... 



31... 

 Sept. 1.... 



2 



3.... 



4.... 



5 . . . . 



6.... 



7.... 



8.... 



9.... 



Total. . 





 

 1 

 

 

 

 1 

 

 

 

 1 

 



40 



Apparently flies are present on the trees several weeks before ovi- 

 position begins. At first they occupy the foliage chiefly, making 

 short flights from leaf to' leaf and resting quietly for long periods. 

 During the preoviposition period, as well as later, they may be seen 

 lapping at the leaves as though extracting food from deposits on the 

 surface. As the time for the beginning of oviposition approaches 

 the flies become more active, and both males and females show a 

 tendency to gather about the nuts. The males habitually select cer- 

 tain nuts on which an individual will take his stand and often remain 

 for hours at a time awaiting the coming of the female, combating, 

 meantime, other males that approach. When a male alights on a nut 

 already tenanted by another male the original occupant attacks it and 

 usually the two rear up on their hind legs, facing each other, and en- 

 gage in a brief but animated bout, belaboring each other with their 

 forelegs. Usually the original occupant is the victor and the would- 

 be interloper flies away. 



A prick made in a walnut with a pin or other sharp point was sure 

 to be found by a male, who, recognizing it evidently as a suitable 

 place for the females to come to oviposit, would immediately begin 

 standing guard over it. In one instance the writer pricked a dozen 

 walnuts on the lower branches of a tree with the point of a small 

 nail. Thereafter for several days a male was on guard at each of the 



