HYMENOPTERA (SAWFLIES). 169 



slugs, of passing out a coat of slime and leaving it and the lime 

 behind. They are best destroyed by the arsenical washes men- 

 tioned in Appendix II. Arsenate of lead was found very suc- 

 cessful in 1897 at the S. E. Agricultural College Fruit-Gardens. 



The Com Sawfly {Cephus pygmcBnis). 



The Com Sawfly belongs to a different section (OepMnce) to 

 either of those mentioned above. The body of this com pest 

 is flattened from side to side, keel-shaped. Its presence as a 

 com pest has long been known, but it is never a very serious 

 pest in this country, as it is sometimes on the Continent. Un- 

 fortunately it has been on the increase this last few years, at 

 least in those districts with which the author is acquainted. 

 All kinds of straw crops are attacked, but C. pygmcBus seems to 

 show a decided preference for wheat. The parent flies appear 

 in June and July ; they have a black-and-yellow-banded body, 

 brighter in the male than in the female; the former sex is 

 rather more than one-third of an inch long, the latter slightly 

 smaller; wing expanse just over half an inch. The female 

 cuts, by means of her saw-like ovipositor, a slit just beneath 

 the developing ear of com, and there places a single egg, 

 closing the hole up as others do in this group. In two weeks, 

 or a little less, there comes from the ovum a small white 

 larva, which at once commences to devour the inner parts of 

 the straw : as the larva grows it works downwards, until 

 about harvest-time it has reached the bottom of the straw, 

 having eaten its way through the successive nodes. When 

 mature it reaches half an inch in length; it is white, and, 

 unlike other Savirfly larvse, it is nearly apodal : a few small 

 lumps below are all that remain of the typical sucker-feet. 

 When the bottom of the straw is reached the larva turns round, 

 and then cuts the straw off an inch or two above the ground as 

 clean as if cut with a sharp penknife. The winter is passed in 

 the stubble, where the larva spins a cocoon of pale loose silk, 



