• REPORT OF THE ENT03I0L0GIST. 573 



INSECTS AFFECTING SMALL GRAINS AND GRASSES. 



By F. M. Webster, Special Agent. 



LETTER OF TRANSMITTAL. 



La Fayette, Ind., November 2, l«86. 

 Sir: I herewith transmit my annual report for tlie current year, containing a 

 continuation of my studies of the Wlicat I&osoma, and a new pest, the Companion 

 Wheat-fly; notes on Me.romyza americana, and some insects affecting Barley; a list 

 of insects frequenting or depredating upon Buckwheat; notes upon the destruetion 

 of timothy meadows by the Glassy Cut-worm; and two enemies of the White 

 Clover. 



As usual, I am under obligation to yourself and assistants for the determination 

 of material, and numberless other favors. 

 Respectfully submitted. 



F. M. WEBSTER, 

 Dr. C. V. Riley, Special Agent. 



Entomologist. 



INSECTS AFFECTI]:^G FALL WHEAT. 



THE WHEAT-STRAW ISOSOMA. 

 (Isosoma tritici Riley.) 



Up to June of the present year matters remained very much as they were left in 

 my previous report, so far as obtaining any additional facts relative to the habits of 

 this species is concerned. Straws, in Avhich grande only had oviposited, failed to 

 furnish adults of any sort, and straws taken from the fields gave only wingless 

 females of tritici. which, as usual with those reared in mid-winter, refused to ovi- 

 posit on wheat plants grown and kept indoors for that purpose. On returning from 

 the South in April, however, we found a limited number of these tritici, which 

 had emerged much later, probably in March, alive in the breeding-cages, and at 

 once ti'ansfeiTed them to young wheat plants gi'OAvn and kept continually under 

 cover, in a corner of our garden, at least tlu*ee-fourths of a mile from any field of 

 either wheat, rye, or barley. This was on the 12th of April. 



From tills time forward until the grain and straw were fully ripened, early the 

 following July, the utmost caution was observed in keeping the plants thoroughly 

 protected from outside insects, and, with the exception of a single Tipulid. which 

 appeared during spring, no msects whatever were at any time observed within the 

 inclosure except the Isosoma. 



On the 2d of June, fifty-one days after the tritici had been placed m the mclosure, 

 a female of grande was observed in the act of ovipositing in the now nearly full- 

 grown straw, and, within the next few days several others were noticed similarly 

 occupied, plac-ing their eggs not only in the upper joint, but m the one below also. 

 Previous to this, and, in fact, since the 21st of May, the latter species had been ob- 

 served continually in the fields, and the belated appearance of these In the inclosure 

 is perhaps due to the fact that their progenitors, the tritici, were of the last to 

 emerge in the spring. Absence from home for two months previous to the date of 

 their removal from the breeding-cage to the young wheat made it impossible to 

 secure them earUer, as it was difficult to get enough then living to carry on the ex- 

 periments, the numerous dead in the cage indicating that the species had been 

 emerging for some time. 



As before stated, the tritici placed in the inclosure were all of them females. 

 Neither could any males be found among those that had previously died, and, 

 moreover, all of the grande were females apparently, as all that were observed at 

 all in the inclosure were ovipositing. Hence the males of either form, if there are 

 any, are still unknown to me.* 



A winged form of Isosoma, seemingly intermediate between tritici and grande, 

 was taken with the latter ia considerable numbers about Bloomington. 111., 

 during May. 1884, and has since been found in the vicinity of La Fayette, Ind.. in 

 both gi-ain fields and grass lands, but in too limited numbers to permit of successful 



* As shown on page 544, we have been more successful in this respect than has Mr. 

 Webster, and three males of tritici were bred in January, 1886. — C. V. R. 



