INSECTS AND DISEASES INJURIOUS TO FOREST TREES. 



where the trees grow closest together, and when we consider 

 that both wind and rain destroy numbers of these the fact 

 of isolated trees, and which, consequently, are most exposed 

 to storms, being comparatively free from attack is not to be 

 wondered at. So far as we at present know, the only way 

 to diminish in any appreciable degree the numbers of this 

 insect is by encouraging as much as possible their 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 Bologne, 

 and 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 this season, parasitic flies and ichneumon attack 

 them wholesale, and a box of caterpillars sent to me the 

 other day revealed the fact that each one had succumbed 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. 



Wireworms. These occasionally do a great deal of 

 damage in beds of seedling trees, particularly Conifers, 

 and in some instances they attack and destroy the seeds 

 before germination. In the case of young Conifers they 

 are gnawed completely through just above or at the ground 

 level, the beds in many instances being strewn with the 

 cut-over plants. Abies nobilis and A. Nordmanniana suffer 

 to a great extent, and I have frequently been at my wit's 

 end to put a stop to the repeated depredations ; but in the 

 case of a newly- formed nursery or freshly made-up seed 



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