INSECT ENEMIES OF EASTERN FORESTS 267 
The adult beetle of Superda discoidea ¥., the hickory Saperda, 
ranges from 10 to 16 mm. in length, the female being larger than the 
male. The male is blackish, beari ing three lines of gr rayish pubescence 
on the thorax and silvery white hairs beneath. The female is reddish 
brown, clothed with yellowish hairs, and the wing covers have two 
spots with a crescent-shaped bar between. The species occurs in the 
Kastern and Central States. The larvae feed gregariously beneath 
the bark of dying or weakened hickories and butternut, making ex- 
iensive meandering mines. 
The adults appear in the spring and oviposit in crevices of the bark 
or in holes in the galleries of scolytid beetles. The larvae feed entirely 
between the bark and wood, destroying the inner bark and making 
extensive interlapping mines packed with fibrous frass. ‘The pupal 
cell 1s constructed in the sapwood or bark, the adult making the exit 
hole. Most of the larvae mature in 1 year, but an ov erlapping of gen- 
erations occurs. Hickory trees attacked by the hickory bark beetle are 
usually found infested by this insect also, and trees which are attacked 
only in the top by bark beetles may be killed outright. 
The adult beetle of Saperda obliqua 8 ay, the alder borer, measures 
from 10 to 15 mm. in length. It is reddish brown, with two darker 
bands along the top of the thorax and four oblique bands on the wing 
covers. The antennae are annulate. It is found in the Lake and 
Northeastern States. Early in the summer the eggs are laid in a small 
hole gnawed through the bark at the base of the shrubs. The young 
larvae feed beneath the bark, often girdling the stem before entering 
the wood. <A considerable swelling takes place at the point of attack 
unless the stem is killed. Much frass is exuded through the enlarged 
egg scar. The larva bores from 3 to 6 inches up through the stem. 
At the top of this mine it pupates above a wad of fibrous frass and 
later the adult gnaws an exit hole. The development is completed in 
fyear. sim parks and ornamental plantings, the alders are frequently 
killed by this borer. Its attack is not general, but it frequently 
becomes locally abundant. 
The adult beetle of the elm borer (Saperda tridentata Oliv.) is 
from 9 to 14 mm. in length and is rather densely clothed with grayish 
pubescence. The thorax and elytra bear narrow orange stripes on the 
sides, and the latter also bear three obliaue cross bars. The species 
occurs in the eastern part of the United States. The adults fly from 
early to late summer, laying eggs in small holes enawed in crevices of 
the bark of weakened or dying elm trees. The larvae feed by boring 
beneath the bark, filling the mines with fibrous frass and completely 
destroying the inner bark and cambium. Usually limbs and injured 
portions of the trees are attacked first and from ‘there the mines are 
pushed into the healthy tissue. The pupal cell is constructed either 
in the sapwood or in the bark. Very little frass is exuded. One year 
is normally required to complete the development, but many larvae 
fail to mature in this period and the generations overlap. 
Park and shade trees are severely ‘injured by this borer, especially 
old, mature trees or those in an unhealthy condition. Trees defoliated 
by the elm leaf beetle or caterpillars and trees closely confined in city 
pavements are susceptible to attack. The death of the tree is usually 
slow, large branches dying one after another. It is very commonly 
associated with trees attacked by the Dutch elm disease. This and the 
