256 



THE WILLOW. 



are often covered with the earth, which the heavy 

 rains wash over them, they present the singular 

 phenomenon of trees which are more or less sub- 

 terranean. The extremities of these branches 

 form sometimes a kind of turf, and the astonished 

 traveller finds himself, as we may say, walking on 

 the top of a tree. Salix herhacea is the species 

 that most frequently presents this remarkable 

 appearance, because it generally grows on steep 

 slopes of loose soil." The leaves are employed 

 in Iceland in the tanning of leather. 



A long list of insects that feed on the Willow 

 is given by Loudon and Selby. Among them 

 the most destructive is the larva or caterpillar of 

 the Goat-moth.* The perfect insect lays, it is 

 said, as many as a thousand eggs at the base of a 

 tree, and the larvae, as soon as they are hatched 

 penetrate the bark, and spend three years of their 

 existence in eating out long galleries in the wood. 

 At first they are exceedingly small, but when 

 full-grown are four inches long, and about an inch 

 in circumference. They are then disgusting in- 

 sects : the body is brownish-red above, yellow 

 beneath, and sprinkled with hairs. When touched 

 the caterpillar discharges from the mouth a fetid 

 acrid fluid, which it is said to use in softening 

 the wood on which it feeds. Before changing 

 to a chrysalis it makes a strong cocoon of chips 

 of wood, and small pieces of bark which it has 

 gnawed off, and awaits its final transformation. 

 The cocoon is placed at the end of the excava- 

 tion, and in contact with the air, so that the per- 

 fect insect has no difficulty in effecting its escape. 

 The moth measures above three inches from the 



Cossus ligniperda. 



