INDIRECT INJURIES CAUSED BY INSECTS. I45 



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 (^Selandrla 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 destruc- 

 tion 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 wiih a very disagreeable and sickening odor. 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 (^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 

 become a pupa, gnaws its way through the cherry, and sometimes not one 

 in a thousand escapes."^ This insect is fortunately rare with us, and has 

 usually been found upon the blackthorn. The cherry-fly also (Tephritis 

 Cerasi) provides a habitation for its maggot in the same fruit, which it 

 invariably spoils.^ 



The different varieties of the plum are every year more or less injured 

 by Aphides; and a Coccus (C. Persica?) sometimes so abounds upon 

 them that every twig is thickly beaded with the red semiglobose bodies of 

 the gravid females, whose progeny in spring exhaust the trees by pumping 

 out the sap. In Germany, as we learn from M. Schmidberger, while the 

 plum trees suffer from having their bark injured by two bark-boring beetles 

 (^Scolytus hamorrhous and S. Pruni), their fruit is destroyad by the larvae 

 of a beetle {Rhynchites cupreus), of a moth (^Carpocapsa nigricana), and 

 of a saw-fly {Tenthredo Morio).* 



The pear tree is liable to have its bark pierced in this country by the 

 larvae of Carpocapsa Wceberana, which often lays the foundation of 

 canker^ ; and in America by those of two beetles (Scolytus pyri, and 

 Strobi Peck^) ; its sap is injuriously drawn off by Psylla piri ; its leaves 

 have their parenchyma eaten away from under the cuticles, so as to give 

 them a blistered appearance, by the larva of the pretty little moth Tinea 

 ClerkeUa L. ; and while the blossoms are rendered abortive by the attacks 

 of the grub of a beetle (Anthonomos pyri Kollar), the fruit is caused to 

 drop off prematurely and rot by the larvae of not fewer than three minute 

 tipulidan flies, (Sciara pyri Schmidberger, Sciara Schmidbergeri Kollar, 

 and Cecidomyia nigra Meigen^,) and also by that of a four small winged 

 fly, observed by Mr. Knight, which would seem to be a saw-fly, and is 

 probably the species which Reaumur saw enter the blossom of a pear 

 before it was quite open, doubtless to deposit its eggs in the embryo fruit. 



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



* Trost Kleiner Beijtrag. 38. 3 Reaum. ii. 477. 



* Kollar on Ins. inj. to Gardeners, k.c. 237. 232. 268. 



* See Observations on this insect in Trans, of Hort. Soc. ii. 25. by W. Spence. 

 6 Westwond, Mod. Classif. of Ins. i. 353. 



' Kollar, ubi supr. 250. 289. 292. 



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