110 INDIRECT INJURIES CAUSED BY INSECTS. 



poor and rich, have their share of enemies in this class. The all-attacking 

 Aphides do not pass over them, and the former especially are sometimes 

 greatly injured by them ; their excrement falling upon the berries renders 

 them clammy and disgusting, and they soon turn quite black from it. In 

 July, 1812, I saw a currant-bush miserably ravaged by a species of Coccus, 

 very much resembling the Coccus of the vine. The eggs were of a beauti- 

 ful pink, and enveloped in a large mass of cotton-like web, which could 

 be drawn out to a considerable length. Sir Joseph Banks once showed 

 me a branch of the same shrub perforated down to the pith by the cater- 

 pillar of JEgeria tipuliformis : the diminished size of the fruit pointing out, 

 as he observed, where this enemy has been at work. In Germany, where, 

 perhaps, this insect is more numerous, it is said not seldom to destroy the 

 larger bushes of the red currant. 1 The foliage of these fruits often suffers 

 much from the black and white caterpillar of Abraxas grossulariata, and 

 sometimes from those of Halias Vauaria ; but their worst and most destruc- 

 tive enemy is that of a small saw-fly (Nematus Grossularice Dahlbom). 

 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 ani- 

 mals 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. 2 



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 Cerast) 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. 3 In some parts of 

 Germany the cherry-tree has an enemy equally injurious. A splendid 

 beetle of the weevil tribe (Rhynchites Bacchus) bores with its rostrum 

 through the half-grown fruit into the soft stone, and there deposits an egg. 

 The grub produced from it feeds upon the kernel, and, when about to 



1 Wiener Verzeich. 8vo. 29. 



2 Fabricius seems to have regarded the saw-fly that feeds upon the sallow (Nematus 

 Caprece), not only as synonymous with that which feeds upon the osier, but also with 

 our little assailant of the gooseberry and currant. Yet it is very evident from Reau- 

 mur's account, whose accuracy may be depended upon, that they are all distinct 

 species. Fabricius's description of the fly 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 two species, he described 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 regarding 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. 



3 Peck's Nat. Hist, of the Shtg-worm, 9. 



