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 hj birds and squirrels, or 

 destroyed by insects. When 

 the sun lies warm in February 

 and March on wooded hillsides, 

 the Rufied 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, Avhich live 

 upon them ; but most of these 

 insects, when occurring in nor- 

 mal numbers, are either harm- 

 less or beneficial rather than 

 injurious. Theu* 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 oflT the twigs ; others destroy branches. The numbers of 

 these insects are regulated by birds. In 189(3 oak pruners 

 {Elaphidion 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 



Fig. 32. — Ruffed Grouse, "biid- 

 diug." 



