130 



desired areas (ig). I'he Department of Economic 

 Zoology in this University has achieved some good re- 

 sults in the larch plantations of the Manchester Corpora- 

 tion catchment area around Lake Thirlmere. Here the 

 Larch Saw-fly is most destructive, and by fastening on 

 the trees large numbers of nesting-lDoxes suitable for Tits, 

 which prey on the larvae of this Insect, direct benefit has 

 resulted. 



Among Molluscs the carnivorous Slug Testacella 

 alone is valuable. It is a dirty white or yellowish form 

 with a small shell situated at the hinder end of the body. 

 In injurious Sings the remams of the shell is always very 

 far forwards and m close relation to the respiratory 

 pore. It is local in this district, but has occurred in 

 several localities. Testacella feeds upon other Slugs, 

 Worms, and dead animal matter, and causes no harm to 

 vegetation., 



Earthworms are true segmented worms and differ 

 from Eelworms. In the course of burrowing Earth- 

 worms let in moisture and air, the subsoil becomes 

 loosened, and direct benefit therefrom is derived. Large 

 quantities of earth are swallowed by them, which they 

 pass out of their bodies m the form of worm casts," 

 commonly seen on lawns and flower -beds. In this 

 manner fresh soil is constantly being brought to the sur- 

 face, and at the same time Earthworms draw numerous 

 leaves and other kinds of vegetation into their burrows 

 which they consume in appreciable quantities. Humus is 

 partly due to the activities of Earthworms — the bringing 

 of soil to the surface and the burying of vegetable 

 material is an important factor in the humus formation, 

 which adds to the general fertility of the land. Darwin 

 calculated that as much as ten tons of soil per annum 

 passes through the bodies of Earthworms and is brought 

 by them to the surface, over each acre of good land. 



AllLLIPEDES (7) belong to the class of Myriapoda 

 which are more closely related to the Insecta than to any 

 other group. Like the Insects, Myriapods are provided 

 with a single pair of feelers or antennae, but they always 

 possess more than six pairs of legs, usually ^ a large 

 number, and never acquire wings. The two main groups 

 of the ]^Iyriapods are the Centipedes or Chilopoda and 

 the Millipedes or Diplopoda. The former, which are 

 beneficial rather than injurious, have a somewhat flattened 



