THE INSECTS OF THE GREEN LANES, 



197 



are interesting microscopical objects, as are also the 

 hairs of the latter. Fig- 139 



The "Saw-flies" are 

 objects less known to the 

 general public, although 

 the farmer is obliged to 

 own a far nearer acquaint- 

 ance with them than he 

 cares about. One species, 

 commonly known as the 

 " Turnip saw-fly," or 

 " Black-jack " (Afhdia 

 spinarium) is exceedingly 

 destructive to the turnip 

 crops. It is the cater- 

 pillar that goes by the 

 name of " Black-jack " 

 from its appearance. In 

 the Eastern counties, 

 this creature often lays 

 waste hundreds of acres 

 of turnips in one season. 

 Nothing, except a hard 

 winter, seems able to 

 arrest its ravages. Some 

 years have been marked 

 as the " canker " year 

 through the extraordi- 

 nary appearance of these 

 costly pests. The insect into which the caterpillar 



Oak Leaf Galls Upper portion, 

 with Oak Spangles; 6, lower 



portion, with Button Galls. 



