AMERICAN PLUM BORER. 3 
FOOD PLANTS. 
This insect does not, by any means, confine its attacks to plum. 
It has been taken feeding upon plum, peach, cherry, Chinese plum 
(Prunus simoni), Kieffer pear, mountain ash, persimmon, apple, 
and Russian mulberry. The writer has found it equally abundant 
on plum, cherry, peach, and apple. It will probably attack the 
trees of any of the common stone or pome fruits when the proper 
conditions are presented. 
FEEDING HABITS AND CHARACTER OF INJURY. 
As has already been stated, the food habits of this insect are of 
especial interest when contrasted with those of other wood-boring 
species. The plum borer prefers trees which are not dead and yet 
are not in a too vigorous condition. The attention of the writer was 
first attracted to the work of this borer by an apple tree upon which 
it had established itself. This tree had been partially girdled by a 
disease commonly known as collar blight. Under the skirt of bark 
bordering the wounded area the borer had begun its work and by 
extending its galleries out into the living tissue had completed the 
girdling of the tree. This seems to be the characteristic form of 
injury for the species. Beginning at some scar, wound, or crevice, 
where a bark scale offers partial protection, the larva works its way 
back into the living tissue, in broad, shallow, irregular galleries just 
beneath the bark. Apple trees partially girdled by collar blight and 
trees injured mechanically by frost or by some other factor offer the 
ideal condition for the work of this borer. Without injury of some 
sort to its host plant the borer rarely succeeds in establishing itself, 
and entirely healthy and uninjured trees are in little danger from its 
attacks. On the other hand, where a tree has suffered injury the 
work of this borer may, in many cases, considerably shorten its life. 
PI. I, a, h, c, shows the character of the galleries and the condition 
of trees most liable to attack. 
DESCRIPTION OF STAGES. 
THE EGG. 
When first deposited the egg appears as a regular oval, opaque 
white body, coarsely punctate. The size is fairly uniform, the average 
for 10 being 0.59 mm. by 0.42 mm. A marked change takes place in 
the appearance of the egg as incubation proceeds. Twenty-four 
hours after deposition the color changes from white to a pinkish tint, 
or in cases where incubation is somewhat delayed to a light brown, 
and in 48 hours to a dull red. In three to four days a slight depres- 
sion appears in the center and 24 hours before hatching the color 
