INDIRECT INJURIES CAUSED BY INSECTS. 197 



The different varieties of the plum are every year 

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

 sica, F.?) 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 oc- 

 casions it to drop off prematurely*. This would seem 

 to be a saw-fly, and is 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 

 {Hornby x cceruleocephala, F.) Linne" denominates the pest 

 of Pomona and the destroyer of the blossoms of the apple, 



a On the Apple and Pear, 158. The beetle Mr. Knight alludes to 

 Is probably the Curcidio oblongus, L„ which ansv/ers his description, 

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

 tract on this subject ( Verhandeling ten bewijze $c. door F. H. van 

 Berck. 8vo. Haarlem 1807) that the great destroyer of the blossoms 

 of their apple- and pear-trees is the larva of another beetle, Curculia 

 Pomorum, L., which from the name and Gyllenhal's addition to the 

 habitat given by Linne— " quas destruit"— should seem to be inju« 

 rious in Sweden also. 



b Reaum. ubi swpr. 47 '5. c On Fruit Trees, 27L 



A On the Apple and Pear, 45, 



