INSECT ENEMIES OF EASTERN FORESTS 247 
as does the twig pruner (/7ypermallus villosus) (p.245). The control 
methods are similar to those used for the latter. 
Encyclops caeruleus (Say), the oak-bark scaler, is a small, slender, 
bright greenish-blue beetle. The head of the larva is extended and 
wider than long, and the ampullae are strongly bilobed and protu- 
berant. It bores in the outer bark of hving white oaks and many other 
hardwoods, causing the dry scales to peel off. Although of no economic 
importance, it 1s frequently found associated with other borers in the 
Eastern States. 
There are various species of beetles belonging to the genera Goes 
and Hanvmoderus that bore in the trunks of trees and are commonly 
known as trunk borers. These are robust, cylindrical, prettily 
blotched or spotted beetles from 11 to 30 mm. in length. The thorax 
is cylindrical, with a spine on each side. The antennae are long and 
the legs rather short and equal in size. The larvae are elongate, cylin- 
drical, of shining texture, having the head longer than wide and very 
depressed and the mandibles obliquely pointed at the apex. The 
pronotum is posteriorly covered with fine velvety-brown asperities, and 
the ampullae bear four rows of finely asperate tubercles. There are 
five species of economic importance that work in the branches or trunks 
of living hardwood trees, making large mines through the heartwood 
and exuding fibrous frass. 
The general features of all species can be treated together. About 
the time the chestnut is in full bloom, the adults emerge, feed on the 
thin bark of young twigs and the bases of leaf petioles, and shortly 
afterward begin to oviposit. The female gnaws oval pits through the 
bark and then inserts in each pit a single egg between the wood and 
inner bark. Within 20 to 30 days the young larvae hatch out and begin 
feeding. Some species, as Goes tigrinus, G. debilis, and G. pulveru- 
lentus, do little feeding beneath the bark but directly enter the sap- 
wood, whereas the others feed beneath the bark through this and the 
following season. After entering the wood the larval mine is extended 
upward through the wood and usually deep into the heartwood. From 
2 to 4 years is required to complete the larval development. During the 
spring of the last year an enlargement of the larval mine is constructed 
and extended outward toward the bark. In this cell pupation takes 
place above a wad of fibrous frass. The adult gnaws its way out 
through wood and bark. During the entire larval feeding period 
fibrous frass is exuded from a hole at the point of the egg scar. 
It rarely happens that these species actually kill the tree in which 
they are working, as so much of the feeding is done in the wood that 
the growing tissue is not greatly damaged. Occasionally Goes pulcher 
girdles the trees or branches, causing their death. The oak sapling 
borer (Hammoderus tesselatus), however, kills a great many young 
oak saplings by entirely cutting them off at the base. Frequently 
young trees are broken off by ice or wind at the point where the heart- 
wood has been destroyed by these larvae. The defects in the resulting 
timber constitute by far the most serious damage. In many localities 
scarcely a matured oak can be cut that does not show one or more of 
the abandoned larval mines. Secondary insects, as carpenter ants, 
occupy the abandoned galleries and enlarge the cavities in the heart- 
wood. The burrows likewise open the heartwood to wood-destroying 
fungi. For control of these species see page 24. 
