574 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



rearing in confinement, and hence what aflSnities it may have with other forms or 

 species is not known. 



A small form of hordei also occurred about La Fayette during the latter part of 

 May, I8H0, on blue grass and timothy, growing up intermixed, and also to a very 

 limited extent on wheat; but this also refused to oviposit in the latter in the breed- 

 ing-cages, and disappeared from the field of both grain and grass altogether in a 

 few days. 



The same locality was repeatedly swept over during the present season, but no 

 hordei could be found. Grande were, however, obtained in considerable numbers 

 from grass lands, but the most careful search failed to reveal any indication that 

 they emerged from these gi-asses or that they oviposit in them. 



It may be proper to state here that in the three years during which I have had 

 these Isosomas under observation they have never been observed ovipositing in 

 chess, nor has an instance been noticed where the straws of this gi'ass have been 

 affected by them. This discrimination on the part of these insects, whereby the 

 stools of wheat are prevented from heading, while those of the grass continue to 

 flourish, may perhaps in part account for the unexpected preponderance of the 

 latter during some seasons, a phenomenon which so sorely taxes the science of the 

 unbotanical farmer. 



There is, however, a species of larva infesting the stems of timothy from the latter 

 part of July to the following spring whose method of work is very similar to that 

 of the Avhe'at-straw worms, but which nevertheless belongs to a different order of 

 insects. It is probably the larva of a species of Languria,* and may readily be dis- 

 •tinguished by the form of the head, by the more slender and less smooth body, and 

 by the presence of well-developed legs on the thoracic segments. 



THE AMERICAN MEROMYZA. 



(Meromyza americana Fitch.) 



Full-grown larvae of this species were observed by us on June 18 of the present 

 year in a field of rye near Kentland, Newton County, Indiana, and we bred adults 

 from straw gi-own near La Fayette about July 21, and again from volunteer wheat 

 in the same field from which the straw had been taken from September 3 to 21. 

 A previous examination of this field made August 31 had revealed the fact that the 

 volunteer wheat plants gi-owing upon a space 1 foot square contained 11 puparia, 

 1 empty case, and 1 two-thirds grown larva. 



On October 5 we found adults in gi-eat numbers (and also adults of a parasite, 

 Ccdinius meromyzoe Forbes) engaged in ovipositing on wheat in a field sown Sep- 

 tember 22, and on going to another field, which had been sown much earlier, we 

 found adults there also, but in less numbers, although the former field had been 

 sown on oat stubble, while the latter field had last produced a crop of wheat. 



In view of these observations and the results of your own breedings from volun- 

 teer wheat sent you from Oxford, Ind., on September 6, 1884, there seems little rea- 

 son to doubt the existence of a third brood of flies, originating, largely at least, in 

 volunteer grain, and emerging therefrom during the month of SeptemlDer. 



As we have elsewhere shown, f the observations of Fitch, Riley, Lintner, Forbes, 

 and ourself in no case have indicated that a tliird brood was improbable, but in 

 some instances strongly presage its existence. 



THE COMPANION WHEAT-FLY. 



Oscinis (?) sp. 



During the latter part of June, 1884, while examining wheat straws in which the 

 larvai of Meromyza americana were at work, we often found several smaller larvae, 

 also dipterous, and so closely associated with the former that we at first suspected 

 them of being parasites. Tliey were almost invariaVjly foiind among the juicy mass 

 of su Instance that had been displaced by their larger consort. 



Securing a supply of affected straws, we cut from each a section about 3 inches 



* Specimens of this larva were forwarded to us by Mr. Webster, but the adult 

 beetle was not bred. The larva was indistinguishable from that of Languria vio- 

 zardi, described by Professor Comstock in the Annual Report of this Department 

 for 1879 under the popular name of "The Clover-stom Borer," as he had reared it 

 from stems of Red Clover at AVashington. Mr. Webster's larvae probably belong to 

 this species, which is figured on Plate I, Fig. 6, of the report just cited, and de- 

 scribed on page 199. — C. V. R. 



f Bulletin No. 9, Purdue University, issued October, 1886. 



