June, '09] JOURNAL OF ECONOMIC ENTOMOLOGY 231 



QUACK GRASS fAGROPYRON), A HOST OF THE 

 HESSIAN FLY^ 

 By Paul Hayhirst 



As far as we know it has not yet been definitely proved that the 

 Hessian fly can breed on any grass besides its three well-known hosts, 

 wheat, rye and barley, although many attempts have been made to 

 shed light on this question. It was, therefore, with unusual interest 

 that puparia, apparently of this species, were accidentally discovered 

 in quack, or couch-grass, Agropyron repens, at Forest Hills, IMass., 

 Nov. 8, 1908. They were particularly numerous on a small piece 

 of cultivated land Avhere this grass had sprung up in early autumn. 

 It must, therefore, have been especially suitable for oviposition when 

 the fall brood of adults were flying. Puparia were found at several 

 other points in this neighborhood, but never in the larger, tougher 

 plants. They were all embedded in the stems just above the roots 

 like the true Hessian fly, and the injured plants showed precisely the 

 same effect. There was no stubble or volunteer grain near the 

 infested grass, and the nearest field of grain was a little rye about a 

 mile east, which was, therefore, not in the direction of the prevailing 

 winds. The U. S. Weather Bureau states that these were S. W. dur- 

 ing September, 1908. It seems improbable that this attack on the 

 quack was accidental from neighboring grain fields. 



We thought it best to rear the adults and to test their specific iden- 

 tity by breeding them on wheat. Acordingly 65 specimens were col- 

 lected from the quack and placed in a vivarium. On Dec. 10th adult 

 males and females began to emerge. A number of these were enclosed 

 over young growing wheat. Eggs were laid freely in the furrows 

 of the dorsal surface of the leaves in the usual way of the true Hes- 

 sian fly. The reddish larvie hatching from these eggs stationed them- 

 selves in the stems just above the roots, and adults of both sexes 

 emerged the following February. Specimens of these flies together 

 with their parents reared from quack were sent to Doctor Felt, an 

 eminent authority on the Cecidomyiidae. He kindly replied as fol- 

 lows : " I have studied the material . . . and I see no reason for 

 not regarding the Mayetiolas reared from Agropyron repeals taken in 

 ihe held, and the descendants therefrom bred on wheat in the insec- 

 tary, as other than the Hessian fly, Mayetiola destructor Say." 



Doctor J. Portsehinsky, Chief of the Bureau of Entomology^ of the 



^Contributions from the Entomological Laboratory of the Bussey Institution, 

 Harvard University, No. 4. 



