10 



BULLETIN 



U. S. DEPAKTMENT OF AGRICULTUEB. 



writer's mind that if the types of all of the early described species 

 now referred to synonymy were in existence to-day and were recog- 

 nizable, vaginicola would be found among them. H. vaginicola 

 was very probably confused with hordei and secalis as well as tritici. 

 The writer's earliest personal records of vaginicola are from col- 

 lections from eastern Ohio 

 in 1912. Since then he 

 has recorded it from 

 Michigan, New York, and 

 Pennsylvania and has 

 been rearing it in confine- 

 ment since 1914. Mr. 

 Desla Bennion sent the 

 writer specimens from 

 Salt Lake as early as 1914 

 and Mr. L. P. Eockwood 

 recently submitted a single 

 gall from Oregon, from 

 which this species has 

 emerged. 



MANNEE OF INJTOBY. 



H. vaginicola affects the 

 plants in a very peculiar 

 way, and only one other 

 species, namely, atlantica, 

 a gall-former in Agrop'i/- 

 ron sp., is known to the 

 writer to affect a plant in 

 a similar manner. The 

 eggs (fig. 8, a) are depos- 

 ited in the tender leaf 

 sheath surrounding the 

 embryonic head. It does 

 not seem possible that the 

 insect can always locate 

 .this delicate structure so 

 easily. The result is that 

 as the plant grows, the 

 leaf sheath surrounding the developing head becomes fleshy and 

 thick instead of remaining thin and leaflike. Later this thick- 

 ened, fleshy leaf becomes hard and woody and compresses the 

 stem to such an extent that little or no sap can reach the develop- 

 ing head. Consequently the head usually protrudes only an inch or 



Tig. 8.- — Eggs of species of Ilarmolita : a, H. vagini- 

 cola j hjH. secalis; o, H. elymicola j d,H. maculataj 

 e, H. poae. All greatly enlarged. (Original.) 



