INDIRECT INJURIES CAUSED BY INSECTS. Ill 



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

 in a thousand escapes. 1 This insect is fortunately rare with us, and has 

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

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

 variably spoils. 2 



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

 by Aphides ; and a Coccus (C. Persic<s ?} 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 hcsmorrhous and S. Pruni), their fruit is destroyed by the larvse 

 of a beetle (Rhynchites cupreusj, of a moth (Carpocapsa nigricana), and of 

 a saw-fly (Tenfhredo 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 4 ; 

 and in America by those of two beetles (Scolytus pyri, and Strobi Peck 5 ) ; 

 its sap is injuriously drawn off by Psylla pyn ; its leaves have their paren- 

 chyma eaten away from under the cuticles, so as to give them a blistered 

 appearance, by the larva of the pretty little moth Tinea Clerkella L. ; and 

 while the blossoms are rendered abortive by the attacks of the grub of a 

 beetle (Antkonomus pyri Kollar), the fruit is caused to drop off prema- 

 turely and rot by the larvae of not fewer than three minute tipulidan flies 

 (Sicara pyri Schmidberger, Sciara Schmidbergeri Kollar, and Cecidomyia 

 nigra Meigen 6 ), 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. He often found in 

 young pears, on opening them, a larva of this genus. 7 A little moth like- 

 wise is mentioned by Mr. Forsyth as very injurious to this tree. 8 



But of all our fruits none is so useful and important as the apple, and 

 none suffers more from insects, which according to Mr. Knight are a more 

 frequent cause of the crops failing than frost. Here, as in the pear-trees, 

 the bark, and consequently the whole tree, suffers from the larvae of 

 Carpocapsa Wceberana, and of Tinea corticella L., as well as of a Scolytus 

 nearly related to S. destructor, but perhaps distinct, which I found infesting 

 it in Guernsey in 1836; and in Austria the larva of another beetle 

 (Trypodendron dispar) pierces into the heart of young healthy trees, and 

 destroyed M. Schmidberger several of his stock. 9 The sap is often 

 injuriously drawn off by Psylla mali 10 ; and by a minute Coccus, of which 

 the female has the exact shape of a mussel-shell (C. arborum linearis 

 Geoffr.), and which Reaumur has accurately described and figured. 11 This 

 species so abounded in 1816 on an apple-tree in my garden, that the whole 

 bark was covered with it in every part ; and I have since been informed 



1 Trost Kleiner Beytrag. 38. 2 Reaum. if. 477. 



3 Kollar on Ins. inf. to Gardeners, &c. 237. 232. 268. 



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



5 Westwood, Mod. Class, of Ins. i. 353. 



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



7 Reaum. ubi supr. 475. 8 Q n Fruit Trees, 271. 

 9 Kollar on Ins. inj. to Gardeners, &c. 256. 



10 Keaum. iv. 69. t 5. f. 6, 7. " Ibid. 278. 



