544 REPORT OF THE COMMISSIONER OF AGRICULTtlRE. 



stumbling-block to our acceptance of this hypliothesis in 1884 before 

 the alternation had been proven, and it so remained until January G, 

 1886, when a male Isosoma was bred by us from the same straws in 

 which gr ancle was observed ovipositing by Mr. Webster at La Fayette 

 August 12. 1885, and which had since been isolated, and from which 

 female tritici v^^ere being bred and were subsequently bred in num- 

 bers. On February 4 another of these males was bred from this lot 

 of straw, and on February G still another, making three in all. In 

 size these males were slightly smaller than the females of tritici, 

 and of course much smaller than qrande. They were all three fully 

 winged, and could have been nothing else than the males of tritici. 

 Attempts were made while they were yet alive to establish this be- 

 yond all peradventure by placing them with living females of tritici 

 bred from the same straws and also with living females bred from 

 straws received from California. The result was unsatisfactory. 

 The males were lively and ran actively about in the breeding-jars, 

 but made no attempt to pair. As soon as they came in contact witli 

 the females they either Hew away or droj^ped as if startled. They 

 were watched, however, only during the daytime from 9 a. m. until 

 4 p. m. , and were in confinement in breeding- jars in the Divisional 

 laboratory. All males died after three or four days, and none of the 

 males issued on the same day with the females, so that one or the 

 other was weak when watched with the opposite sex. It is also 

 probable that the artificial conditions of a vivarium are unfavorable 

 to proper development or maturity of the specimens, and that free- 

 dom and sunlight are essential to coition. 



This breeding of the males, although not perfectly satisfactory, re- 

 moves tlie last obstacle to the acceptance of the fact of alternation of 

 generations with this species; for we must now call it a single species. 

 The summary of its life-history in Indiana is as follows: 



In March and April there issue from old last year's straws, either 

 stubble or volunteer, wingless females of the tritici form, with, in 

 some seasons, males. These oviposit in growing wheat. In June the 

 winged females of the grande form issue from this same wheat, with, 

 so far as known, no males. These oviposit in the now nearly grown 

 straws of wheat, and from these eggs hatch larvae which mature be- 

 fore winter and give forth adults of the tritici form early the ensu- 

 ing spring. 



From this summary it will be seen that it is the grande form alone 

 which does the damage in Indiana; and supposing this relationship 

 to hold wherever the species occurs, it effectually relieves those north- 

 ern regions where only spring wheat is grown i' rom any anticipation 

 of injury, and indicates the obvious remedy of destruction of stubble 

 and volunteer grain in the cultivation of winter wheat. In locali- 

 ties where both winter and spring wheat are grown we should expect 

 to find the insect the most numerous. 



Bearing out this suggestion, we may state that we have received 

 the insect from no portion of the country in which spring wheat ex- 

 clusively is grown. 



We have used the above qualifying clause as to the alternation of 

 generation in these two forms in all sections where the species occurs, 

 for the reason that while grande has been found only in Blooming- 

 ton and Normal, 111., and Oxford and La Fayette, Ind., tritici has 

 been sent to us from Virginia, India.na, Illinois, Tennessee, Missouri, 

 Kansas, Califorida, and Washington Territory. 



Mr. J. F. Donkin, of Grayson, Stanislaus County, California, wroto 



