REPORT OF THE ENTOMOLOGIIST AND BOTANIST. 177 



on grain crops at Ottawa. In 1890 this insect was very injurious in Kentucky, and 

 was well worked up by Prof. H. Garman, who published an excellent bulletin thereon 

 under the name 0. variabilis, Loew. {Bull. SO, Ky. Ag. Ex. Sn.) Prof. Garman writes : 

 " I think it very likely that the Oscinis carbonaria of Coquillett's notes is the 0. 

 variabilis observed by you and me in 1890. I never felt quite satisfied with the deter- 

 mination. The flies were abundant here at that time, but have not been seen since." The 

 life history in many particulars agrees with those of the Wheat-stem Maggot and the 

 Hessian Fly, but there is still some uncertainty as to the range of variation in its habits. 

 Such part of the life history ashadbeen worked outup to 1890is given in the Annual Report 

 of the Experimental Farms for that year. In Prof. Lugger's Second Report, 1896, what 

 is apparently an allied species is described with the important diffe- 

 rence of habit that the larva bores inside the stems of wheat caus- 

 ing them to break down, and before that producing the appearance 

 known as " dead heads." This attack was not observed at Ottawa 

 when the American Frit-fly was so abundant, but the family to which 

 this insect belongs is one which is remarkable for the diversity 

 which is found in the feeding habits of the larvae. 



Remedies. — The remedies for this insect are the same as those 

 for the Hessian Fly, viz., the late sowing of fall wheat, the har- 

 rowing of stubble (or in the West the burning over or ploughing 

 down of stubble), and the application of special fertilizers in spring. 



As some of my correspondents have had difiiculty in distin- 

 guishing between the American Frit-fly, the Hessian Fly and the 

 root-infesting larvae of the Wheat-stem Maggot, I quote from my ^FritV^p!pt^a?e-° 

 annual report of 1890 the chief differences: — enlarged. 



" The three insects are easily distinguishable in all their stages. 

 In the larval or maggot stages, in which they do all their injury to crops, they may be 

 known by the following characters : — 



1. The American Frit-fly : — Maggot long and slender, yellowish-white with two 

 small but distinct black hook like jaws. The last division of the body bears two little 

 knob-like processes. Length when full grown Jg- of an inch. 



2. The Wheat-stem Maggot : — This resembles the last named in shape and structure, 

 but is conspicuously different by reason of its clear glassy green colour, and also by its 

 much larger size, J of an inch when full grown. 



3. The Hessian Fly : — This is proportionately much broader than the other twv), of 

 a clearer white than the American Frit-fly maggot and nearly always shows a green 

 stripe down the centre. Instead of the two hook-like black jaws which are present in 

 the two previously mentioned maggots, the Hessian Fly larva has a horny forked organ 

 sometimes called the ' breast-bone.' Length when full-grown, ^ of an inch. 



"In the chrysalis stages the differences are equally marked : — 



1. The American Frit-fly. — The pupa-case is shaped as shown above (Fig. 6) and 

 is of a pale chestnut brown. 



2. The Wheat-stem Maggot. — Changes to a pale translucent pale green pupa-case 

 (Fig. 4c). 



3. T/ie Hessian Fly. — The pupa-cases of this insect are of a deep rich brown, like 

 small flax seeds (Figs. 2 and 3), and it is in this stage that farmers will most easily recog- 

 nize the Hessian FI3-. 



" The perfect insects are very unlike. The American Frit-fly is shown at Fig. 5 

 very much enlarged. The colours are black and yellowish-white. It is a very small 

 insect, large specimens being only ^\ of an inch in length. They are extremely active 

 and hard to observe. The fly of the Wheat-stem Maggot is a slender yellowish-oreen 

 fly i of an inch in length, with three dark lines down the back , eyes golden green 

 (Fig. id). The Hessian Fly is a delicate dusky gnat, well shown in Miss Ormerod's 

 excellent figure where it is represented magnified and enlarged (Fig. 1)." 

 86—12 



