260 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
ing galleries packed with granular frass in the living bast tissue, some- 
times reaching the xylem. ‘Two years are sometimes required to com- 
plete the life cycle. 
The feeding causes the outer bark to scale off, and occasionally 
wounds penetrate into the cambium, deadening large patches of bark, 
which finally fall off and open the wood to attack by other insects. 
This borer may prove to be of importance in the transmission of 
Dutch elm disease. Attack by the elm borer (Saperda tridentata 
Oliv.) often follows the work of this species. 
The adult of the sugar-maple borer (G/ycobius speciosus (Say) ) 
isa large, robust, somewhat elongate beetle from 23 to 25 mm. in length, 
black, marked with bright- -yellow cross bands. The head and tip of 
the elytra are entirely ‘yellow, though the latter has a black spot in 
the center. One of the bands near the base of the wings 1s W-shaped. 
The larva is rather large and robust, having the head w vider than long. 
There are three ocelli on each side, and the apex of the mandible is 
rounded. The pronotum is posteriorly reticulate and rugulose and 
extends forward medianly; the ampullae are flat and dull “eranulate. 
Legs are present. It excavates long mines beneath the bark of living 
hard maples, exuding the frass, together with much moisture. It is 
present in the Northeastern States and south through the Appa- 
lachians. 
The eggs are laid under bark scales or in crevices of the bark from 
which point the larvae mine directly between the bark and the wood, 
cutting a deep channel obliquely transverse to the grain of the wood. 
These mines fr equently girdle and kill the branches or smaller trees. 
During the second year the larva finally bores deep into the wood to 
construct a pupal cell, the exit from which is opened prior to pupa- 
tion. Aside from directly killing parts of the tree, the healing of the 
larval mines causes large unsightly ridges, w ounds, or gall- like swell- 
ing on the bark sur face of the branches that live. Watery exudations 
and sawdust are associated with the presence of living larvae. Noth- 
ing in the way of control can be done in the forest ; for control in shade 
trees, see page 24. 3 
The adult cottonwood borer (Plectrodera scalator (F.)) is a large, 
subeylindrical, robust beetle from 25 to 30 mim. in length, black thickly 
checkered with white pubescence in broken transverse rows. The 
thorax is cylindrical with a small spine on each side. The larva is an 
elongate, robust, cylindrical borer, having the head flattened, longer 
than wide, and the anterior ventral mar ein very much thickened. The 
pronotum is posteriorly dark, velvety “pubescent, and the ampullae 
bear four rows of tubercles. This larva feeds in the wood at the base 
of living poplars and willows, exuding quantities of fibrous frass. It 
occurs in the Central and Southern States. 
The adults appear in midsummer and feed on tender bark before 
depositing the eggs in small pits gnawed through the bark of living 
trees near the surface of the round. The larvae mine both beneath 
the bark and in the wood, although feeding most of the time beneath 
the bark and exuding considerable frass. Before constructing the 
pupal cell, the larva makes a hole through the bark for the adult to 
emerge. A period of 2 years is required to complete the development. 
Large numbers of young poplar and willow trees are killed where this 
insect becomes abundant. The larvae often completely girdle the bases 
