INSECTS AND DISEASES INJURIOUS TO FOREST TREES. 



of the infested specimen. The formation of this excrescence 

 is brought about by the female aphis piercing with her beak, 

 or sucker, one of the buds, and the drawing off the sap, 

 the consequence being an unusual growth at that part. 



When the young larvae appear they also, by piercing the 

 gall, extract the juices, and the gall enlarging soon causes 

 the larvae to become embedded at the bases of the leaves, 

 which, by this time, have become curiously malformed. The 

 insects are scarcely ^ in. long. 



The only remedy is to collect the cone-like excrescences 

 and have them destroyed, unless in the case of badly-infested 

 trees, which should be cut down and burned. 



The Laburnum Moth (Gemiostema laburnella) is fairly 

 abundant in England, at least; and, in some instances, 

 every leaf of a tree has been eaten almost wholesale by the 

 caterpillars of this pretty moth. The insect is about in. 

 long, and & in. across the fully expanded wing. It is of a 

 silvery- white colour. 



The greenish-grey caterpillars are about in. long. 



By burning the attacked leaves great numbers of the 

 caterpillars may be destroyed, while, by shaking the trees in 

 May and August, the moths will fly out, and may be caught 

 in a butterfly net. 



Wood Leopard Moth (Zeuzera &sculi). (Page 202.) The 

 caterpillar of this beautiful inoth is very destructive to the 

 beech, ash, birch, elm, walnut, privet, &c., and which it bores 

 into, eating and living on the wood. Usually young trees or 

 the branches of old specimens are attacked, and the tunnel- 

 ling is confined in the former, either to the pithy centre or 

 the soft wood near the bark. The moths appear about mid- 

 July, and the female, by piercing the bark with her power- 

 ful ovipositors, deposits her eggs, one in each hole. Three 

 years are required for the caterpillar to arrive at maturity 

 when it is nearly 2 in. long. Both in form and colour 

 the leopard moth is particularly elegant, the head and 

 thorax being covered with a thick white pile, the body with 

 a black down, fringed with white at each joint. The wings 

 are white with yellowish-brown veins, a row of rounded 

 bluish spots running between every two. 



'209 P 



