INSECT ENEMIES OF EASTERN FORESTS 325 
Hylocurus the first joint of the antenna is club-shaped, and the eyes 
are short, oval, and widely separated both above and below, whereas 
in Micracis the basal joint of the antenna is flattened and ornamented 
with long hairs, the eyes are large, elongate, and either contiguous, or 
narrowly or moderately separated beneath. 
The burrows made by the species of these two genera are rather 
similar in form to those of other scolytids, but differ in being in the 
sapwood (Type 7) or in the pith (Type 6) (see pp. 298-299). The en- 
trance gallery proceeds directly through the bark into the sapwood, or 
farther, into the pith. Here a slightly enlarged nuptial chamber is 
constructed, and from this, one or several egg galleries arise. In the 
wood the galleries extend obliquely with little regard either to growth 
rings or the grain of the wood. In the pith one or more egg galleries 
extend in each direction through the pith. The larvae feed on the 
wood or pith and doubtless on the hyphae of fungi growing in this 
material. Usually species of Hylocurus and Micracis are of little 
economic importance, as with one exception they occur most commonly 
in small or moderate-sized branches. Species of Zylocurus especially 
favor the recently cut, dying, or dead limbs of hickory as host mate- 
rial, and all but one of the eastern species have been taken from such 
material. One species, /7. /angston?, is more commonly found in larger 
material and in other hosts. Species of Micrasis are found in a 
variety of hardwoods, particularly in twigs and smaller branches. 
Hylocurus langstoni has been taken in Mississippi, Texas, Mary- 
land, and Virginia, and the known hosts include honeylocust, hack- 
berry, mulberry, and elm. This species attacks the trunks of dying 
or recently dead trees and often enters poles and fence posts utilized 
while still green. The larvae bore through the sapwood, producing 
an injury very similar to that caused by powder-post beetles, as the 
larval mines are often closely crowded together, are packed with 
a fine, powdery frass, and may riddle the entire sapwood. Removal 
of the bark or thorough seasoning of posts and poles before setting in 
the soil will probably prevent damage. 
[ylocurus rudis has been taken from hickory, maple, chestnut, 
and hackberry, and is widely distributed, though not common, having 
been collected in Michigan, Maryland, North Carolina, Georgia, and 
Mississippi. 4. béorbis is known from New York, Pennsylvania, 
Maryland, District of Columbia, and North Carolina. Hickory is 
the only known host. 4. becornis and H. harnedi have been found 
only in hickory in Mississippi. 4. spadix occurs in hickory in Penn- 
sylvania and North Carolina. 
Micracis swainei is widely distributed, having been taken in 
willow or redbud in Maryland, West Virginia, Mississippi, Louisiana, 
Texas, Arizona, and California. d/. populi is known only from 
New York, where it was taken in poplar shoots. M. suturalis 
infests redbud, walnut, and papaw in Illinois, Michigan, Ohio, Penn- 
sylvania, Maryland, Virginia, West Virginia, and the District of Co- 
lumbia. MM. meridianus is found in willow and redbud in 
Mississippi, the District of Columbia, and Virginia. df. opacicollis 
is a pith borer in dead sprouts or shoots of oak, maple, redbud, and 
cypress. It is common and widely distributed from Massachusetts to 
Michigan and Kansas and south to Florida and Texas. J/. nanula 
is closely related to opacicollis but is more southern in its distri- 
