193 INDIRECT INJURIES CAUSED BY INSECTS. 



but having consumed the leaf on which they were born, 

 they separate from each other, and the work of devasta- 

 tion proceeds with such rapidity, that frequently, where 

 many families are produced on the same bush, nothing 

 of the leaves is left but the veins, and all the fruit for 

 that year is spoiled^. 



Upon the leaves of the cherry, which usually succeeds 

 the gooseberry, in common with those of the pear and 

 several other fruit-trees, the slimy larva of another saw- 

 fly {T. Cerasi, L.) makes its repast, yet without being 

 the cause of any very material injury. But in North 

 America a second species nearly related to it, known 

 there by the name of the slug-worm^ has become preva- 

 lent to such a degree as to threaten the destruction not 

 only of the cherry, but also of the pear, quince, and plum. 

 In 1797 they were so numerous that the smaller trees 

 were covered by them ; and a breeze of air passing 

 through those on which they abounded became charged 

 with a very disagreeable and sickening odour. Twenty 

 or thirty were to be seen on a single leaf; and many 

 trees, being quite stripped, were obliged to put forth 



" Fabricius seems fo have regarded the saw-fly that feeds upon the sal- 

 low {Tenthredo Capreas), not only as synonymous with that which feeds 

 upon the oskr, but also wish our little assailant of i\\e gooseberry and cur- 

 rant. Yet it is very evident from Reaumur's account, whose accuracy 

 may be depended upon, that they are all distinct species. Fabricius's 

 description of the ^^ agrees with the insect of the gooseberry, but that 

 which he has given of the larva belongs to the animal inhabiting the sal- 

 low. Probably, confounding the two species, he described the imago 

 from the insect of the former, and tiie larva (if he did not copy from 

 Reaumur or Linne) fror.i that of the latter. Linne was correct in regard- 

 ing Reaumur's three insects as distinct species, though he appears to be 

 mistaken in referring to him under T.Jlava, as the saw-fly of the currant 

 and gooseberry is not wholly yellow. 



