29 



too much reliance must not be placed on these distinctions, as there are 

 other supposed species of these insects attacking wheat of whose larvae 

 and pupa? we know nothing, but with our present knowledge the facts 

 just given are the l)est that can now be offered the farmer in order to 

 enable him to separate the different main enemies of his grain and 

 receive whatever practical benefit is possible from what information is 

 now available, leaving future studies to throw more light upon his 

 problems. The adults can be easily separated from those of the pre- 

 ceding species b}'' their smaller size, and from the next by their smaller 

 size and the color of the legs, which in I. hard el are honey yellow. 

 The larvfe are also smaller than those of the following species and may 

 or may not cause galls and deformities in the straw. The adults of the 

 summer form of the preceding and those of the following species are 

 abroad at the same time as are those of this species during the last 

 days of May and early June. 



While fig. 9 illustrates the effect of the larva? on a wheat plant, there 

 are so many variations from this that it is at present impossible to 

 separate these two gall-forming species by their effect on the straw. 



THE BARLEY STRAW-WORM. 



{Tsosoma hordei Harris. Fig. 10.) 



Up to 1896 this species was confused with the preceding and the 

 term "joint- worm" applied thereto. The fact is, Harris seems not to 

 have given this name to his species at all, but on the other hand Doc- 

 tor Fitch applied it to his /. tritici^ and it was owing to the confusion 

 of these two insects that the name became misapplied, and 1 have here 

 given Harris's species the name "barley straw-worm," in accordance 

 with the name Jiordei. 



PREVIOUS RECORDS OF THE INSECT. 



Of all of our described species of Isosoma this was the earliest 

 known and was for many ^'•ears supposed to be the only species infest- 

 ing cultivated grains or, in fact, inhabiting this country, as it was con- 

 sidered a parasite on the real depredator, presumed to be some kind 

 of a two-winged fly, and was actualh^ described by Dr. W. T. Harris 

 in 1830 as a parasite, under the name IcJinewnon hordei/' Doctor 

 Harris certainly seems to have been aware of the fact that as early 

 as 1821 Mr. James Worth, of Sharon, Bucks County, Pa., found 

 larvaj clearly belonging to some species of Isosoma affecting the culms 

 of wheat "near the root, where they caused enlargements of the 

 stem;"^ and in 1823, Mr. Joseph E. Muse, of Cambridge (Eastern 

 Shore), Md., reared an insect, also from wheat, which he termed a 



*«ISrew England Farmer, July 23, 1830; Ins. Mass., 1841, pp. 434-437, 

 ^ American Farmer, vol. 4, p. 394. 



