INDIRECT INJURIES CAUSED BY INSECTS. 111 
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,? 
The different varieties of the plum are every year more or less injured 
by Aphides ; and a Coccus (C. Persice ?) 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 hemorrhous and S. Pruni), their fruit is destroyed by the larve 
of a beetle (Rhynchites cupreus), of a moth (Carpocapsa nigricana), and of 
a saw-fly (Zenthredo Morio).§ 
The pear-tree is liable to have its bark pierced in this country by the 
larvae of Carpocapsa Weeberana, 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 pyri; 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 (Anthonomus pyri KGllar), 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 K6llar, 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. He often found in 
young pears, on opening them, a larva of this genus.” A little moth like- 
wise is mentioned by Mr. Forsyth as very injurious to this tree.® 
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 larve of 
Carpocapsa Weberana, and of Tinea corticella L,, as well as of a Scolytus 
nearly related to iS. 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 IM. Schmidbenrger several of his stock.® The sap is often 
injuriously drawn off by Psylla mali! ; and by a minute Coceus, of which 
the female has the exact shape of a mussel-shell (C. arborum linearis 
Geoffr.), and which Reaumur has accurately described and figured. 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. 88. ® Reaum. ii, 477. 
5 Killar on Ins. inj. to Gardeners, &c. 237, 232. 268. 
* See observations on this insect in Trans. of Hort. Soc. ii. 25. by W. Spence, 
5 Westwood, Mod. Class. of Ins. i. 853. y 
® Kollar, ubi supr. 250. 289. 292, 
aum. ubi supr. 475. 8 On Fruit Trees, 271, 
ve Kollar on Ins. inj. to Gardeners, &c. 256. 
® Reaum, iv. 69, t. 5. f. 6, 7. 14 Thid. 278. 
