Plants as Affected by Antmal Parasites. 149 
bottom to prevent the rabbits from passing under. It should 
be high enough to reach above the surface of the deepest 
snow. 
Orchard trees may be protected against rabbits by inclos- 
ing the trunks with the devices mentioned under sunscald 
(186). Smearing the stems with blood has also been recom- 
mended. 
275. Woodchucks are often troublesome to growing 
crops, but as they are seldom numerous, shooting or trap- 
ping generally suffices to prevent serious damage. Moles 
are very troublesome in some localities by eating the roots 
of plants. They may be largely controlled by trapping with 
mole-traps. 
276. Birds are often troublesome by eating unharvested 
fruits. Inclosing the trees or plants with fish netting, when 
this is practicable, is perhaps the most satisfactory prevent- 
ive. The netting may be purchased at a low price, and the 
same piece may be used several seasons. 
b— By insects, worms, slugs and snails. As worms, 
slugs and snails work the same kind of injuries as some 
insects, and are controllable by the same methods, we do 
not distinguish between them in the following paragraphs. 
277. Many Insects are Beneficial by destroying other 
insects, or by promoting pollination (151). We should not, 
therefore, wage indiscriminate warfare upon all insects. 
278. Methods of Preventing Insect Ravages to 
plants are various, as inclosing the plants; entrapping, re- 
pelling or removing the insects, or destroying them by 
means of insecticides. The important question, in the case 
of any injurious insect, is by which one of these methods it 
may be most effectually and cheaply controlled. 
