270 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
area of the pronotum and the entire ampullae are covered with rather 
stiff, brownish, velvety pubescence. It is legless. It feeds in the 
trunks of living red maples. 
In midsummer the adults appear and lay their eggs at the base of 
a small dead twig or in a wound. The larvae bore directly into the 
sapwood and later into the heart of the stem, completely destroying 
the center of the tree. A swelling or gall forms about the wound. 
The second summer a straight excavation is made directly upward 
or downward at the extr emity of which the pupal cell is constructed. 
The frass is tightly packed behind the larva, and the adult gnaws 
through this and emerges near the point where the egg was laid. 
This insect never kills the tree outright but causes deformities and 
wounds through which secondary insects or fungi gain entrance and 
continue the destruction. 4t is not uncommon to find 75 percent of 
red maples in a neighborhood infested and many of them broken off 
at the point of injury. 
AX ylotrechus quadrimaculatus is an elongate, moderately robust 
beetle, from 12 to 15 mm. in length, having the thorax black, marked 
with four distinct yellowish spots and the elytra pale brown with 
indistinct whitish markings. It occurs in the Eastern States. Its 
larva resembles that of Y. aceris, but only the perimeter of the ampul- 
Jae are velvety pubescent. 
In midsummer the adults appear and lay their eggs at the axil of 
a small twig where the branch is to be girdled. The young larvae 
feed beneath the bark, often girdling and killing the branch in a short 
time. Then by concentric circles cut toward the center the branch 
is almost severed, except for the few strands of wood not cut between 
the concentric burrows. On reaching the pith, the larva bores toward 
the tip of the branch, packing the mine tightly with granular frass. 
About 10 inches from the end of the branch a simple pupal cell is con- 
structed, the adult gnawing out through the wood and bark. The 
development is completed in 1 year. 
In certain localities this insect becomes abundant enough to girdle 
many branches on beech and birch shade trees and sometimes maple. 
It is not uncommon to find branches 2 inches thick cut off.by this larva. 
To control this borer, collect branches and destroy them during the 
winter. 
NX ylotrechus obliteratus Lec., the poplar-butt borer, is an elongate. 
moderately robust beetle, from 10 to 18 mm. in length, uniformly dark, 
with yellow cross bands at the anterior and posterior margins of the 
thorax and three across the elytra—the first oblique, the middle curved, 
and the last transverse. The larva of this beetle also resembles that 
of X. aceris, but the velvety pubescence is finer. It feeds in the base 
of living poplar trees, chiefly aspen. 
The adults fly very late in summer, laying their eggs in irregularities 
of the bark er exposed wood of living poplars. The young larvae 
feed that fall beneath the bark, and the next season enter the wood, 
where they work for several years. The entire heartwood is com- 
pletely honeycombed because, after a tree is once attacked, adults con- 
tinue to lay eggs in the same butt until the tree dies. A great propor- 
tion of the feeding is done beneath the surface of the ground. The 
