142 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



growths at the base of the gall. The species has undoubtedly been 

 present in the Eastern States for many years and entomologists simply 

 assumed that these galls were those of /. tritici. This is not at all 

 strange or unusual since anyone but those very familiar with the group 

 may easily confuse a number of the species. 



Prof. R. W. Doane describes a species from Utah that forms galls 

 in the leaf-sheath surrounding the head of wheat, as /. vaginicolum 

 n. sp.^ Upon request Professor Doane kindly sent specimens of his 

 species and they were received just as this paper was being prepared. 

 They agree in every structural detail with the species that occurs here 

 in the East. The effect upon the plant, as described by Professor 

 Doane also^agrees entirely with the injury as noted here in the Eastern 

 States. 



A number of interesting facts have come to light as a result of cage 

 breeding with individual species. One of the most important is that, 

 up to the present, no species can be induced to breed on any other 

 plant than its own particular host. This fact was ascertained by 

 making repeated efforts to rear in confinement a given species in plants 

 other than its own host. Before this could be attempted, however, 

 sufficient breeding had to be done to definitely establish the identity 

 of a species. It seems now to be a definitely established fact that the 

 three species occurring in wheat cannot be induced to breed in any 

 other plant. The same is true of those occurring in rye and barley, 

 and on down the list. This is a very important economic fact, since 

 it simplifies greatly measures for control. 



Elymus species is by far the most favored host with Isosoma, from 

 which no less than seven species have been reared. Wheat and Agro- 

 pyron sp. come next with three species each; rye and blue-grass {Poa 

 pratensis) follow with two each; barley, timothy (Phleum pratense), 

 orchard grass (Dactylis glomerata), Poa sp., Festuca sp., and Bromus 

 sp., have a species of Isosoma common to each. 



The list just mentioned contains new species and may. not and 

 very probably does not include all species that have been previously 

 described from this country. Some species that were very common 

 years ago are almost extinct today, as seems to be the case with 7. 

 hordei. This species was evidently very numerous and destructive 

 many years ago in the barley growing sections of the East, and today 

 it has almost or quite entirely disappeared from these localities. 

 This seems to be directly traceable to the greatly decreased acreage 

 of barley over a large part of this territory. This is also probably true 

 for the species occurring in rye. Whenever a certain grain crop ceases 

 to be grown consecutively in contiguous fields, the future of the species 



1 Jour, of Econ. Ent., vol, IX, No. 4. 



