SCALE-FELT, OR BEECH W.OOLLY APHIS. 367 



in length, it is lens-shaped, being flattish below and highly 

 convex above. The mouth is on the underside of the body, 

 and composed of three hair-like appendages, united to form a 

 long sucking tube ; with it this insect pierces the bark and 

 sucks the sap. She has no power of locomotion. Almost 

 immediately after leaving the egg, she covers her body with a 

 white, felted, waxy secretion, which forms an excellent coat, 

 impervious to rain. Within this coat, she lives, lays her eggs 

 and dies. 



The larvae are very tiny and active, and scarcely visible to 

 the naked eye. They possess three pairs of legs and a pair of 

 antennae, and like their parent are yellow. They can move 

 over the bark of the tree, but usually settle down under the 

 body of their dying or dead parent, preferring the deepest 

 parts of the bark-fissures, where they remain sucking the sap. 

 Each larva protects its body with wool, which is added to that 

 produced by previous generations. The secretion therefore 

 gradually thickens and spreads over the tree-trunk, forming a 

 more or less continuous mass. Larvae wandering over the 

 tJark are borne by the wind or by birds or insects to other 

 trees and spread the infection. The larvae hibernate, 

 and eventually lose their legs and antennae and become 

 parthenogenetic ? . 



Young and old beech trees are attacked, the sheltered side of 

 exposed trees being selected. The attack sometimes lasts for 

 years without apparent injury to the tree, while others die, the 

 foliage gradually becoming discoloured and thin and the smaller 

 branches dying, the bark peeling off the branches and trunk. 



In the extensive beech forests near Brussels, the absence of 

 thinning is said to favour the disease, and where thinnings are 

 made it is generally absent. It is extremely rare in the beech 

 woods of the Chiltern Hills, which are usually over-thinned. 



Remedial measures. As given above. 



2. Lecanium hemicryphum, Dalm. 



Lecanium differs from Coccus by the ? swelling up over the 

 eggs and its back being chitinised to form the scale. This scale- 

 insect and the accompanying fungus, Apiosporium pinophyttum, 

 Tuckel., nourished by the honeydew, cause a black, paste-like 



