IHDIRECT INJURIES CAUSED BY INSECTS. 199 



more or less injured by Aphides ; and a Coccus (C. Per- 

 sicte ?} 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. 



The blossoms of our pear-trees, as we learn from 

 Mr. Knight, are often rendered abortive by the grub of 

 a brown beetle : and a considerable quantity of its fruit 

 is destroyed by that of a small four-winged fly, which 

 occasions it to drop off prematurely*. This would seem 

 to be a saw-fly, and b probably the species which Reau- 

 mur 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 b . A little moth likewise is mentioned by 

 Mr. Forsyth as very injurious to this tree c . 



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 d are a more frequent cause of 

 the crops failing than frost. The figure-of-eight moth 

 (Episema c<Erukocephala\ Linne denominates the pest of 

 Pomona and the destroyer of the blossoms of the apple, 

 pear, and cherry. He also mentions another (Tinea 

 CorticeUd) as inhabiting apple-bearing trees under the 

 bark. And Reaumur has given us the history of a spe- 



* On the Apple and Pear, 153. The beetle Mr. Knight alludes to 

 is probably the Polydroms oHongus, which answers his description, 

 and is common on pear-trees. In Holland, it is stated in a little 

 tract on tbif subject (VerkamdeGmg fern bewyse <$c. door F. H. van 

 Berck . 8 vo. Haarlem 1 807), that the great destroyer of the blossoms 

 of their apple- and pear-trees is the larva of another weevil, Aniho- 

 nomus Poncorxiir, which from the name and GyUenhaTs addition to 

 the habitat given by Linne " quas destniit " should seem to be 

 injurious in Sweden also. * Reaurn. tc&i supr. 4J5. 



e On Fruit Trees, , * On OK Apple and Pemr, 43. 



