Insects of Shade Trees and Their Control. 69 
growing and changes to a chrysalis within its burrow (fig. 48, d). 
When it becomes mature, which happens during the period between 
May and September, the pupa or chrysalis forces its way partly out 
of the burrow (fig. 48, 7), its skin splits open, and the leopardlike, 
spotted white moth (fig. 48, a, b) come out of it. Immediately after 
mating the female begins egg laying. As many as 800 eggs were 
observed to have been laid by a single female. The eggs are laid 
singly and in groups of three or more in crevices of the rough bark, 
from which they hatch about 10 days later and the issuing larvee 
begin to burrow their tunnels toward the heart of the wood, thus 
completing the two-year life cycle. 
Methods of control—No easy method of wholesale destruction of 
this insect is known at present. Badly infested trees and limbs 
should be cut and burned promptly lest the borers migrate from them 
to the healthy wood. Many young and highly prized trees, showing 
only a few burrows, have been saved from death and even further 
injury by killing the borers in them with carbon disulphid injected 
into the burrows (p. 14). A flexible wire in many cases can be em- 
ployed to advantage for killing borers in their burrows by probing. 
Clean culture, prompt attention, and simultaneous community work 
are necessary for effective control. Farmers’ Bulletin 708 contains 
- full information on this insect. 
CARPENTER WORM.” 
How destructive—Although it rarely kills trees, the large bur- 
rows up to one-half inch wide made by the carpenter worm in the 
very heart of trees produce serious deformities, which render the 
trees unsightly. Oak, chestnut, maple, locust, and cottonwood are 
among the trees most likely to suffer from it. 
Indication of presence.—Infestation is shown by the wilting of 
smaller twigs, strings of frass dangling from holes in the bark, the 
large gallery (fig. 49, 9), and, when present, the inhabiting worm, 
which is a large, vivid, reddish-white caterpillar (fig. 49, 7) up to 
nearly 3 inches in length, greenish beneath, with scattered, long, 
fine hairs on the body and with head shining black. 
Seasonal history and habits.—It takes this insect about three years 
to complete its life round, which accounts for the presence of cater- 
pillars in badly infested wood at all seasons of the year. In an oval 
cell made by the caterpillar at the outer end of the gallery just be- 
fore completing growth, transformation to the chrysalis (fig. 49, 6) 
_ takes place in May or June. After about two weeks’ life as such the 
chrysalis wriggles partly out of the hole in the tree (fig. 49, 5) and 
® Prionoxystus robiniae Peck. 
