THE PEARS OF NEW YORK 119 
inconspicuous as they rest during the day on the bark of the pear-tree 
which they closely resemble; they fly only at dusk. The moth lays its 
eggs on leaves or the fruit itself and the young larvae immediately begin 
work on the nearest pear. Control consists in spraying with arsenate of 
lead. Two and sometimes three sprayings are necessary. The most 
important spraying is made just after the blossoms fall, while the calyx- 
cup is still open, so that the poison will lodge in the blossom-end of the 
upturned pear. Codling moth was once a most serious pest of the pear, 
but is now easily kept under control by seasonal applications of arsenate 
of lead. 
The pear-slug (Caliroa cerasi Linnaeus), a generation ago, before 
spraying was common, did much damage to the pear in New York, but is 
now a negligible pest except in the orchards of the indifferent or slothful 
since it is easily controlled by spraying. The slugs are small, dark green 
shiny creatures which eat the surface of the leaves of pear, cherry, and 
plum. They devour the upper surface of the leaf leaving the veins and 
the tissues of the lower surface, which turn brown so that the infested 
tree has the aspect of having been scorched by fire. The slugs molt and 
finally lose their shiny coat and dirty green color, the full-grown larvae 
becoming clear yellow. The adult is one of the numerous saw-flys. Eggs 
are laid within the tissues of the leaves. There are two or three generations 
inaseason. The slugs are most common in the hottest part of the summer 
or late in the summer. This pest is easily kept in check by applications 
of arsenate of lead. 
The foliage of the pear, in common with that of the apple, is often 
seriously injured by a mite (Eriophyes pyri Pgst.) which burrows into 
the tissues of the leaves. The mites attack the young leaves causing 
reddish blisters which turn black. The blisters are thickened spots which 
are found to have a corky texture. The young fruits are sometimes 
attacked, in which case they are badly malformed. The mites are of 
microscopic size and can be seen only by the aid of a magnifying glass. 
They hibernate under the scales of the leaf-buds, and are thus ready to 
attack the young leaves as soon as they unfold, which they do by eating 
their way in from the under side and then by their work cause the char- 
acteristic swellings. As they mature, the mites come out and move to new. 
places and start more colonies. In the autumn, they find their way to the 
maturing buds and go into winter quarters. An application of lime-sulphur 
solution at winter strength usually disposes of the mites; that put on for 
