14 BULLETIN 254, U. S. DEPARTMENT OF AGRICULTURE. 



around Columbia, Mo., "in such numbers that they could be gath- 

 ered up by the bushel." * Strong winds in midsummer no doubt are 

 responsible in many cases for what may seem a natural migration. 



ENEMIES. 



PARASITES. 



Probably the most effective enemies of the sharp-headed grain leaf- 

 hopper are its egg parasites, two species of which were reared in great 

 numbers during the summer of 1914, while the writer was stationed 

 at Tempe, Ariz. Both of these egg parasites were new to science, and 

 Mr. J. C. Crawford 2 has described one as Gonatocerus gibsoni; the 

 other Mr. A. A. Girault will describe as AbbeUa auriscutellum. Had 

 it not been for these two egg parasites considerable damage would 

 probably have been done by the jassid during the summer months. 

 One of these parasites, Gonatocerus gibsoni, not only held the species 

 in check but practically eradicated the pest in the Salt River Valley 

 of Arizona. In this valley there was from 75 to 95 per cent of 

 parasitism among the eggs of the second generation of the gram jassid 

 between May 15 and June 15. Mr. J. H. Newton, a temporary 

 assistant in the Bureau of Entomology at Tempe, found an 85 per cent 

 parasitism from several hundred egg pockets examined. 



Mr. George G. Ainslie, while in Florida during the spring of 1914, 

 reared two species of egg parasites ; one of these, reared in consider- 

 able numbers, has been determined by Mr. Gahan as Brachistella 

 acuminata Ashm. Mr. Ainslie recorded a 79 per cent parasitism 

 among eggs examined. Mr. E,. A. Vickery reports having reared many 

 parasites of Ufens niger Ashm., as determined by Girault. Five or six 

 were reared from each egg. 



There are many parasites which affect the Jassidse and it is quite 

 likely that this species comes in for its share. Although none has 

 been recorded as having been reared from the grain leafhopper, yet 

 in all probability some of the members of the families Proctotrypidse 

 and Dryinidse materially help in suppressing its numbers. Several 

 adults of Athysanus exitiosus Uhl. were taken which were parasitized 

 by one of the Proctotrypidse which appeared in the form of an external 

 sacklike structure within which the parasite sucked the juices from 

 the abdomen of the host. These adults of A. exitiosus were swept 

 from fields where the grain jassid was very numerous. In the report 

 of the Hawaiian entomologist and in the papers of Perkins and 

 others may be found accounts of various parasites of the Jassidse. 

 The dipterous genus Pipunculus contains parasites of leafhoppers 

 and according to Giard they are parasitic especially upon the family 

 Jassidas. The order Strepsiptera (the twisted-wing insects) contains 



!0p. cit.,p. 20. 



2 Crawford, J. C. Descriptions of new Hymenoptera, No. 9. In Proc. U. S. Nat. Mus., v. 48, pp. 577- 

 586, sep. no. 2087, May 3, 1915. Gonatocerus gibsoni, new species, p. 586. 



