382 RAVAGES OF INSECTS. 



banks of the Eavensbonrne, in Kent, were extensively 

 stripped of their leaves by a saw-fly caterpillar, very like 

 the preceding, but of a larger size. (J. E.) It appears to 

 be the same as one figured by Eeaumur* (Selandria Alni? 

 Stephexs). 



Another slimy caterpillar of a saw-fly, allied to that of 

 the cherry (Terithredo Cerasi), is called the slug-worm in 

 North America, where it has increased so numerously as to 

 threaten the entire destruction of fruit-trees, including the 

 cherry, plum, pear, and quince. Where they are numerous, 

 the air becomes loaded with a disagreeable and sickly efflu- 

 vium. The history of this orchard pest has been admirably 

 written by Professor Peck.f 



When a turnip crop has been fortunate enough to escape 

 the ravages committed on it in the seed-leaf by a small 

 jumping beetle {Haltica nemorum, Illiger), and by a root 

 weevil (A^edi/us contractus, Stephens), a no less formidable 

 depredator sometimes appears in a caterpillar belonging 

 to the saw-fly family (Tenthredinidce), and apparently of the 

 genus Afhalia. An instance is recorded by Marshall, in the 

 Philosophical Transactions, of man}" thousand acres having 

 had to be ploughed up on account of the devastations 

 caused by these insects. It is, he informs us, the general 

 opinion in Norfolk that they come from over-sea ; and a 

 farmer averred that he saw them arrive in clouds so as to 

 darken the air, while the fishermen reported that they had 

 repeatedly witnessed flights of them pass over their heads 

 when they were at a distance from land. On the beach and 

 the cliffs, indeed, they lay in heaps, so that the}^ might have 

 been taken up with shovels ; while three miles inland they 

 crowded together like a swarm of bees. J 



We have little doubt, however, that these details are put 

 in an inverse order ; as frequently occurs in histories of the 

 proceedings of insects by those but little acquainted with 

 their habits. Insects of this family, indeed, seldom fly far, 

 and could not at all events cross the sea, unless it might be 



* Eeaumm", vol. v., pi. 11, fig. 1, 2. 



t Nat. Hist, of the Slug-Worm, Boston, 1799. 



X Phil. Trans., vol. Ixxiii. p. 317. 



