124 PROTECTION OF WOODS 



fungus finding a ready inlet through the wounds caused by 

 the aphis. At first the insects are wingless, but they acquire 

 wings in late summer, and then spread to other larch and to 

 the spruce. 



Nothing can be done on a large scale against this insect, 

 and one must trust to keeping larch healthy by growing it 

 only in favourable places. Nursery plants, if attacked, may 

 be sprayed with paraffin emulsion. 



Beech woolly aphis (Coccus fagi). 



This scale insect attacks beech, and is becoming a serious 

 pest, often killing fine old trees. It is covered with a white 

 felt, which is very conspicuous on the bark where the insect 

 sits and sucks the sap. Valuable trees in parks may be saved 

 by scrubbing them from top to bottom, wherever the insect 

 is seen, with the paraffin emulsion. Further details may be 

 found in the Board of Agriculture leaflet No. 140. 



Chermes Cooleyi. 



This insect has recently appeared on Douglas fir, and in 

 America it alternates between Douglas fir and Sitka spruce, 

 forming destructive galls on the latter. It has not yet been 

 observed on Sitka in this country, but it is necessary to take 

 immediate action against it, especially on nursery plants of 

 Douglas fir. The upper surfaces of needles of infected plants 

 present a mottled appearance due to discolouration caused by 

 the sucking of the insect. Sometimes the needles are bent. On 

 the under side small patches of white wool are found, under 

 which lie the Chermes. In winter small black oval specks 

 surrounded by a fringe of wool may be found, these being the 

 wintering larvae. 



Infected plants, when lifted from the nursery, should be 

 dipped in a barrel containing soft soap and water. The soap 

 should be dissolved in two pints of boiling water, one gallon 

 of cold water being afterwards added. Dipping should last 

 from i to 5 minutes according to the size of the bundles, and 

 they should then be suspended, roots up, to drip. 



