REPORT OF THE ENTOMOLOGIST AND BOTANIST. 229 



"This pest has existed here at least forty years, and I can see no appreciable increase 

 or decrease. It causes considerable loss in this vicinity, but so far no remedy seems to 

 be generally applicable. Possibly deep ploughing might do much, or burning the stems 

 in gaiden plots." — J. E. Wetmore. 



THE WHEAT-STEM SAW-FLY. 



(^Cephus pygmceits, L.) 



Attack. — Slender, white grubs. Head rounded, yellowish, with the mandibles dark- 

 ened. Body swollen at the first two joints after the head and tapering very slightly to 

 the end, which is terminated by a short, blunt tubercle with a darkened and hardened 

 tip. This Monsieur Herpin describes as a tubular appendage, which is capable of being 

 protruded like a telescope, and assists the insect in its progress within the tube of the 

 straw. Beneath the first three segments of the body are three pairs of rudimentary 

 thoracic feet. These larvae are found inside stems of wheat. When full-grown they are 

 nearly half an inch in length and have by that time bored through all or most of the 

 knots in the stem, leaving a discoloured tunnel extending from the top joint down to 

 the root, where, when mature, they spin thin transparent cocoons in which they pass the 

 winter and change to pupte the following summer. 



In November, 1889, Prof. Comstock published a bulletin (Cor?ie^^ Univ. Coll. o/Agr., 

 Bull. 11.) "On a Saw-fly Borer in Wheat," in which he gives a full account of a remark- 

 able outbreak of Cephus pygmceus oiT the Cornell University farm, when nearly five per 

 cent of the wheat in a field was infested. In the Canadian Entomologist for 1890, 

 page 40, Mr. W. Hague Harrington records that in 1887 he took a specimen of this 

 insect at Ottawa, and that he had received specimens taken at Buffalo, N.Y., in the 

 middle of June, 1888, and again at the same place and season the following year. With 

 the exception of these records, I have been unable to find any mention of specimens being 

 taken in America. On the 5th July, 1895, at Indian Head, N.W.T., I collected 

 specimens of the perfect insect by sweeping the flowers of the Tumbling Mustard which 

 grew in the greatest abundance just outside the Experimental Farm. At that time no 

 injury by the larvae was noticeable on the wheat growing in the district, nor has any 

 report of injury attributable to it been received since from that district; but on the 

 6th of August last Mr. John Wenman, of Souris, Man., sent a packet of wheat stems 

 containing nearly full grown larvaa which answered in every particular to those of 

 Cephus pygmoiiis. Mr. Wenman was written to for full particulars of the occurrence, 

 and the following letter was received : — 



"Souris, Man., Sept. 2. — In reply to your favour of the 12th ultimo, I beg to inform 

 you that I have looked several times for more specimens of the injured stems of wheat, 

 but the field which was most visibly affected had been cut the day before your letter 

 came, and I could not secure good specimens. You ask how it was that I noticed the 

 injury. I observed that some straws were lying down or lodged here and there, and, up- 

 on examining these stems, I found in nearly every instance that the straw was discoloured 

 and broken between the first and second joints. We had had hail a day or two before. 

 On following up inside the affected stems, I found in most cases the grub which you saw 

 in the sample sent, about half an inch long, head brownish and body cream-coloured. In 

 one case I found the grub had worked through all the joints up to the head of grain. I 

 looked for this pest in several of my neighbours' fields. I saw a little in one field. The 

 damage resulting from this attack, however, is so far, I am sure, not appreciable, but 

 pi'ecautions must, of course, be taken, and I shall be on the qui vive for any further 

 visitation." 



The specimens of straw sent by Mr. Wenman contained larvae which were nearly or 

 quite full-<;rown o.n the 12th of August, but only a small proportion of these stems had 

 been tunnelled up to the top joint. The larvae were some distance above the root, but 

 judging from the state of maturity of the straw, they would have descended very soon 

 to the root to form the cocoons in which they pass the winter. 



