178 HARDY CONIFEROUS TREES. 



able and splendid insects — 5. gigas being black and yellow of 

 colour and like our common wasp, while ^. juvencus is of a 

 shining steel-blue, with reddish markings on the male. The 

 larvai are stout white grubs, which bore obliquely towards the 

 heart of the tree, and often the galleries are in such numbers 

 that the tree is killed thereby, and the timber rendered useless 

 in consequence. I have found S. juvencus very plentiful on 

 the Scotch and cluster pines, in Kent. Where wood wasps 

 abound, dead and dying trees should be removed before the 

 images appear in summer. 



Abies nobilis, A. amabilis, and A. lasiocarpa^ particularly the 

 former, are subject to the attacks of an insect nearly allied to 

 that which causes the American blight on apple trees. The 

 attacked portions, generally the buds or base of the leaves, 

 present gouty, usually cup-shaped swellings, and which, with 

 the growth of the shoots, increase proportionally in size. 

 When cut into, the swollen portions are of a spongy appear- 

 ance, and these unsightly deformities not only tell hardly on 

 the health of the trees effected, but render them utterly value- 

 less from either an ornamental or commercial standpoint. 

 An application of fir-tree oil has been found useful at the 

 initial stage of the disease. 



Wireworms injure seedling conifers of most kinds by 

 gnawing the tender stems through at or above ground level. 

 Amongst the rarer conifers Abies nobilis, A. Nordrnanniana^ A. 

 grandts, Pinus Cembra, P. Strobus, and P. Pinaster, are often 

 attacked. Paring and burning the nursery soil, or top- 

 dressing with gas-lime, are fairly successful methods of 

 keeping the wireworm in check ; but after the seedlings 

 appear above ground, pieces of buried carrot, potato, or oil- 

 cake, act as excellent traps. 



The above insects are only such as are commonly met with 

 and commit most damage in this country, but there are many 

 others. 



