UTILITY OF BIRDS IN WOODLANDS. 99 
THE TREE PRUNERS. 
If the young tree escapes or survives the assaults of its 
many enemies, and grows vigorously, it is prone to an over- 
production of fruit or leaves. Orchardists and some foresters 
practise pruning, and believe that when it is judiciously done 
it is good for the tree. Nature has many ways of pruning. 
Superfluous buds are nipped off by birds and squirrels, or 
destroyed by insects. When 
the sun lies warm in February 
and March on wooded hillsides, 
the Ruffed Grouse or Partridge 
may be seen “budding” on the 
wild apple trees, alders, pop- 
lars, and birches. In May the 
Rose-breasted Grosbeak and the 
Purple Finch attack both buds 
and blossoms, scattering snowy 
petals far and wide. We have 
seen that all trees have numer- 
ous insect enemies, which live 
upon them; but most of these 
insects, when occurring in nor- 
mal numbers, are either harm- ig. 32.— Ruffed Grouse, “ bud- 
less or beneficial rather than ane 
injurious. ' Their interests, like those of the birds, are iden- 
tical with those of the tree which supplies them with suste- 
nance. A few leaf-eating caterpillars may be a benefit to 
the tree, by removing surplus foliage, and thus checking a 
too vigorous development, which otherwise might be injuri- 
ous. Other insects, if not too numerous, may destroy the 
surplus fruit or seed, and thus direct the energies of the tree 
toward perfecting larger and better fruit. Certain insects 
cut off the twigs ; others destroy branches. The numbers of 
these insects are regulated by birds. In 1896 oak pruners 
(Hlaphidion villosum) were numerous in eastern Massachu- 
setts. They attacked several species of oaks, hickories, and 
maples. They also assailed the apple trees. Their occur- 
rence in numbers seems to be periodical, and thus the trees 
