Several borers occasionally infest cherry trees of which the peach borer[72] (_Sanninoidea exitiosa_ Say.) is the most troublesome. Larvae of the peach borer are frequently found in both Sweet and Sour Cherries, more particularly in Sweet Cherries, in eastern orchards. Fortunately this pest is not as rife with the cherry as with peaches and plums. Its work may be prevented by thorough cultivation, by mounding the trees and, according to some, by the use of a covering of tar or of obnoxious or poisonous washes. Usually preventive measures are not effective, however, and the borer must be destroyed--best done by digging it out with a knife and wire. Since the pest is easily discovered through the exudation of gum mixed with sawdust or excreta, close to the surface or just beneath the ground, its presence can be detected in time to prevent its doing much damage. The lesser peach borer[73] (_Sesia pictipes_ Grote & Robinson) often attacks old or weakened cherry trees, working in the growing tissues of the trunk anywhere from the ground to the main branches. The worm is much like the common peach borer, known by all, but is smaller, rarely reaching the length of four-fifths of an inch when full grown. The flat-headed apple tree borer[74] (_Chrysobothris femorata_ Fabricius) is a common pest in wild cherries and sometimes seriously attacks the cultivated species. It is treated as is the peach borer. The shot-hole borer[75] (_Eccoptogaster rugulosus_ Ratzeburg), though seldom injuring healthy trees, is very often a serious menace in old or decrepit cherry trees. It may be looked upon, however, as an effect rather than a cause. The peach bark-beetle[76] (_Phlæotribus liminaris_ Harris) is very similar in its work to the shot-hole borer and like it attacks only diseased and decrepit trees. All cherry-growers are familiar with the small, dark green, slimy slugs which feed on the surface of the leaves of the cherry, possibly more common on the foliage of pears, eating out the soft tissues and leaving but the skeleton of the leaf. If the slugs are numerous the tree may be defoliated or if the leaves remain the foliage looks as if scorched. The adult of this slug is a sawfly (_Caliroa_ (_Eriocampoides_) _cerasi_ Linnaeus) which lays its eggs within the tissue of the leaves. Despite the fact that it is easily destroyed by any of the arsenical sprays or by dusting with lime this slug everywhere does much damage to cherries.