WORMS AS SCAVENGERS. 205 



so do the wood-wasps which abound throughout Europe 

 and North America. 



The titmouse and woodpecker are sometimes accused 

 of injuring trees, but it seems unjustly, for they are said 

 never to bore into healthy bark. There are grubs beneath, 

 however well they may look, and it is for these they tap the 

 wood. At the same time, when a tree is diseased, they 

 help on the mischief by making a hole in the tainted wood, 

 where they build their nests and open a way for the rain to 

 penetrate. 



Worms may be said to be very perfect scavengers as far as 

 their powers go, since they not only remove refuse, but turn 

 it to good account as manure, and that without rendering 

 themselves disagreeable, which is more than can be said for 

 some other creatures. They are omnivorous, and besides 

 dragging large quantities of leaves down into their burrows, 

 as linings as well as food, they also feed on decayed 

 flowers, even their own dead comrades, and in fact decaying 

 matter of all kinds. They add largely to the organic matter 

 of the soil, and therefore to its fertility, not only by the 

 enormous quantity of leaves they carry down, but by burying 

 bones, shells, leaves, twigs, and refuse of all kinds beneath 

 their castings. The leaves they feed upon are torn into 

 small shreds, partially digested and mixed with earth, and it 

 is this which gives vegetable mould its dark tint. 



Slugs and snails hardly deserve any notice as scavengers, 

 since, though they do eat fallen leaves, they live chiefly 

 on sound ones, as the gardener knows to his cost. 



