INSECTS Injurious to conifers. 



165 



brushwood and upper layer of needles under the infected trees in 

 the winter with the contained cocoons, and conveying to a spot 

 where it may be safely burned. A very serious objection to 

 this pla^n is that it deprives the soil of its natural surface- 

 covering of needles, and if persisted in for a long time it will 

 injure the health of the trees. It should not be resorted to 

 without good cause, and when other remedies cannot be adopted. 

 The removal of brushwood, &c., as opposed to this covering of 

 needles, is alv/ays valuable for the prevention of insects. 



There are a large number of other defoliating insects common 

 in England, as the moths Fidonia piniaria and Trachea pi7ii- 

 perda, which are rarely, if ever, reported as doing noticeable 

 damage. They are occasionally very common, more particularly 

 the former, and it remains to be seen if their presence does not 

 sometimes tell injuriously on the trees. A favourite device of 

 the continental foresters to keep down caterpillar-attack is that 

 of letting swine run loose in the forest. They are zealous 

 searchers for and devourers of all pupa3 and larvae which come 

 within their reach ; but, unfortunately, the cocoons of Lopliyrus 

 are too leathery to be attacked by them. 



Laech-minee. 



A special form of injury is that inflicted on Larch-needles 

 by the larvjE of a tiny moth, Coleophora laricella, which 

 lays its eggs at the end of June on the needles of the lower 

 branches of Larches about ten to fourteen years old. The 

 caterpillar mines into and feeds upon the interior of the 

 needle, which becomes dry, yellow, and twisted ; it then bites off 

 the tip and detaches the needle about its middle, so as to form 

 a tube in which it lives and passes the winter, concealed in a 

 crack or under a bark-scale. In the spring it feeds on the new 

 needles, and enlarges its tube by spinning a fresh needle along its 

 side, biting it off and hollowing out the adjacent surfaces ; in this 

 tube it changes to a pupa, and ultimately to a moth. This insect 

 is common in many English Larch-plantations, whose foliage, 

 when the attack is bad, has a dull, withered look which is very 

 conspicuous ; it does not kill the tree, but keeps it year after 

 year in an unhealthy condition. 



Practical treatment is difficult ; picking off the injured shoots 

 is very troublesome, and the only successful plan is to remove 



