Insect Enemies of Trees 205 



treatment is quite out of the question. Many observers 

 are under the impression that the caterpillar is most abun- 

 dant where the trees grow closest together, and when we 

 consider that both wind and rain destroy numbers of these, 

 the fact of isolated trees, which, consequently, are most 

 exposed to storms, being comparatively free from attack is 

 not to be wondered at. So far as we know at present, the 

 only way to diminish in any appreciable degree the numbers 

 of this insect is by encouraging as much as possible its 

 enemies. 



The rook, jackdaw, starling, thrush and sparrow help 

 immensely in destroying the caterpillars, and the occupants 

 of a rookery will frequently in a few hours clear the pest 

 from the trees over a considerable area of woodland. The 

 same has been noted with regard to the starling, and I have 

 frequently seen the trees over an infested area almost black 

 with this particular bird when in the act of feeding on the 

 caterpillars. 



In support of this recommendation it may be stated that 

 insects are far less numerous in the forests of St. Germain, 

 Senart and Fontainebleau than in the Bois de Boulogne, 

 where, of course, small birds are scarcer. 



Sometimes with the oak leaf roller moth its excessive 

 number proves the means of its extinction, the foliage being 

 devoured before the caterpillars are fully fed ; while, as is 

 usual at the season of attack, parasitic flies and ichneumons 

 destroy them wholesale, and a box of caterpillars sent to 

 me the other day revealed the fact that each one had suc- 

 cumbed to the attacks of one of these enemies. 



The life history of this moth is full of interest, and the 

 curious manner in which it rolls up the leaves is well worthy 

 of study. 



The Felted Beech Coccus (Cryptococcus Fagi). Judging 

 from the numerous specimens of the beech coccus that are 

 being forwarded to me for identification, and the inquiries 

 as to how this insect pest may be dealt with, its presence in 

 almost every part of the country is indicated. It was only 

 in 1862 that Dr. Balfour reported the presence of this coccus 

 in Scotland, and I remember well how the beautiful beech 



