334 Forty-fourth Report of the State Museum 



[For a more extended notice of this insect, see Fifth Report on the 



Insects of New York, 1889, pp. 78-85; pp. 220-227 of 42d St. Mub. 



Kept.] 



A Saw-fly Borer in Wheat. 



Another introduced insect pest, long known in Europe for its inju- 

 ries to wheat and rye, has been brought to notice the past year. It 

 bears abroad the common name of the " corn saw-fly,*' which may not 

 be used by us as it would be misleading, since with us " corn " is 

 applied only to the maize or Indian corn, while in England it is used 

 collectively for all of the cereals or farinaceous food-plants which grow 

 in ears, viz., wheat, rye, barley, oats, and maize. Its scientific name is 

 Cephus pygmeus (Linn.). 



It was discovered two years ago (in 1887) infesting wheat on the 

 Cornell University Farm, at Ithaca, where it has already become 

 extremely abundant, but strangely, has not been observed, so far as 

 known, elsewhere. Professor Comstock has made it the subject of a 

 Special Bulletin — No. XI, November, 1889, in which a full account 

 of the insect is given. The larva, hatching from the egg deposited 

 in a slit made by the ovipositor of the female fly usually in the upper 

 portion of the stalk, four to five days before its heading out, burrows 

 within, working its way both upward and downward while feeding on 

 the inner portion, and passing successively through all of the joints. 

 Indications of its presence seldom appear before the first week in 

 July, when it has penetrated to the first joint above the ground, at 

 which time a discoloration beneath it may be noticed. When much 

 of the inner portion of the straw has been eaten away, the stalk is 

 liable to be broken and thrown to the ground by high winds that may 

 prevail. 



At the time of harvest, nearly all of the larvse hj,ve burrowed 

 downward to the surface of the ground, where a cell is excavated and 

 closed at the top \^ith borings, and a cocoon is spun of fine silk. 

 Here, after the cutting of the grain, it remains within the stubble, 

 hibernating in its larval stage, and not assuming its pupal form until 

 the following spring — in March or April. Some time in May the 

 winged insect emerges from the pupa, and appears abroad upon the 

 wing. 



Professor Comstock reports that somewhat under five per cent of 

 the wheat straws have been found to contain the insect. He does not 

 find its injury to be so great as reported by European writers. Care- 

 ful weighing kernels of infested and uninfested heads, shows 

 but a very moderate amount of difference in weight. Perhaps the 

 rye crop might be more seriously affected by it. It is an insect that 



