The Vertebrata come within the scope of our subject, chiefly as destructive agents which cause wounds or devour young shoots and foliage, &c. Rabbits and other burrowing animals injure roots, squirrels and birds snip off buds, horned cattle strip off bark, and so forth.
Grapholitha) eat the buds or the roots (e.g.
They may occur on all parts, buds, leaves, stems or roots, as shown by the numerous species of Cynips on oak, Phylloxera on vines, &c. The local damage is small, - but the general injury to assimilation, absorption and other functions, may be important if the numbers increase.
Bruising by a cartwheel, insects-having started a callus on which adventitious buds arise, or to the destruction of buds at an early stage.
Then, stores of food-material being accumulated at the injured place, other buds arise at the base of or around the injured one.