REPORT OF TEE ENTOMOLOGIST AND BOTANIST 193 



SESSIONAL PAPER No. 16 



seeded before June 3 was attacked, and practically all was ruined, and later seedinga 

 although free from the pest gave light crops of soft wheat. Parasites have not been 

 observed as yet, and there seems to be a steady increase in the numbers of this very 

 serious pest of our wheat crop. I may mention that I saw Joint Worm flies on the 

 wing on May 23. — J. A. Clark.' 



Specimens of the galls were sent from Prince Edward Island and such of the flies 

 as were reared proved to be the Wheat Joint Worm, Isosoma tntici, Pitch, but from 

 the difference in the appearance of the galls it would seem likely that another species 

 was also at work on wheat in Prince Edward Island. No specimens of Isosoma hoi-dei, 

 Harris, were received, nor were there any complaints of injury by joint worms to 

 barley. It is not likely that the Wheat Joint Worm will attack either barley or oats. 

 There is apparently only one brood of the Wheat Joint Worm in Canada, the lai-vae 

 of which winter in the straw, for the most part so near to the ground that when the 

 crop is cut the greater portion of them are left in the stubble. It has been recom- 

 mended as a remedy for Joint Worms to burn over the stubble or to plough it down 

 deeply for the destruction of the contained larvas, and the disposal by burning or 

 feeding of the galls or hardened portions of the straw which become separated in 

 threshing. There is great variation in the extent of the sv/elling which results from 

 the attacks of these larvaj. Frequently the galls are hardly noticeable, but the tissues 

 of the stem are thickened and become brittle so that they break from the rest of the 

 straw when threshed. These and all straw from an infested crop should be either fed or 

 burnt before the ensuing spring. As is pointed out above by Mr. Clark, the farmers 

 of Prince Edward Island are getting into the way of seeding down their wheat lands 

 with clover and grasses, so that either burning of stubble or ploughing down cannot 

 be adopted where the land is to be left in hay. A more extensive cultivation of clover 

 than has been the practice in the past in Prince Edward Island is highly desirable, 

 but while the Wheat Joint Worm is abundant and increasing in destructiveness, 

 some modification of the ordinary practice is decidedly advisable and the benefit of 

 sowing clover as a nitrogen-gatherer, might still be preserved to a large extent 

 by sowing a few pounds of clover seed with all grain crops and then plough- 

 ing this down with the stubble either in the first autumn or the following 

 year. In fighting against insects it frequently becomes advisable to modify accepted 

 agricultural practices so as to control a pest which has become unusually abundant 

 at a special locality. By examining the stubble of an infested crop of wheat it could 

 soon be seen whether or not the galls were located near the base of the stem or so 

 high up that they would be carried with the straw. The location of the gall will vary 

 with the season in the same way that the point of attack by the Hessian Fly varies. 

 In late cold springs the attacks of both of these insects are lower down, in the case 

 of the Hessian Fly being sometimes entirely confined to the root shoots, while in 

 other years the larvaj may be found one or two joints up the stem from the base. 



It is important that the farmers of Prince Edward Island should now come to- 

 gether and discuss methods of prevention for this insect, so that some wholesale, 

 vigorous and concerted action may be taken to prevent the further increase of this 

 insect which is now becoming of importance to the whole Island. 



The perfect insect of the Wheat Joint Worm is a minute, shining, black, four- 

 winged fly, only one-tenth of an inch in length with clear wings and pale legs. The 

 larvae are slender, footless grubs, one-eighth of an Inch long with perceptible brown 

 jaws. These occur only inside the galls on the stem and vary in number from 4 or 5 

 to as many as a dozen in a single gall. The galls as a rule occur just above the first 

 or second joint above the root. Nearly all of the larvae winter unchanged inside the 

 galls, but occasionally a small proportion change to flies and emerge late in autimin. 



The Grain Aphis, Macrosiphum granaria, Kirby. — There was an unusual amount 

 of interest and considerable alarm in the Northwestern provinces last summer con- 

 cerning gi-aln plant lice and several letters were received asking If specimens sent 

 were the so-called ' Green Bug ' which was causing such a great sensation in the 



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