INDIRECT INJUllIES CAUSED BY INSECTS. 163 



(^Nematus Grossularice Dalilbom). This larva is of a green 

 colour, shagreened as it were with minute black tubercles, 

 which it loses at its last moult. The fly attaches its eggs in 

 rows to the under side of the leaves. When first hatched, 

 the little animals feed in society ; but having consumed the 

 leaf on which they were born, they separate from each other, 

 and the work of devastation 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 {^Selandria 

 Cerasi) 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 prevalent 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 fresh 

 foliage, thus anticipating the supply of the succeeding year, 

 and cutting off the prospect of fruit. ^ — In some parts of 

 Germany the cherry-tree has an enemy equally injurious. 

 A splendid beetle of the weevil tribe (Rliynchites Bacchus) 

 bores with its rostrum through the half-grown fruit into the 

 soft stone, and there deposits an egg. The grub produced 



1 Fabriclus seems to have regarded the saw-fly that feeds upon the sallow 

 {Nematus Caprece), not only as synonymous with that which feeds upon the oszer, 

 but also with our little assailaiit of the gooseberry and currant. Yet it is very 

 evident from Reaumur's account, whose accuracy may be depended upon, that 

 they are all distinct specie?. Fabricius's description of the Jiy agrees with the 

 insect of the gooseberry, but that which he has given of the larva belongs to the 

 animal inhabiting the sallow. Probably, confounding the tw^o species, he de- 

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

 from Reaumur or Linne) from that of the latter. Linne was correct in re- 

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

 mistaken in referring to him under N. flavus, as the saw-fly of the currant and 

 gooseberry is not wholly yellow. 



2 Peck's Naf. Hist, of the Slug-worm, 9. 



M 2 



