Courtesy Duke Univ. Sch. For. 
Figure 131.—Adults of Neoclytus mucronatus 
mucronatus. 
are most severely damaged. Living trees, healthy or injured, are attacked. A strong 
preference is shown for trees that have partially succumbed to former attacks. The 
adult is from 20 to 28 mm long, grayish black or reddish brown, and densely 
clothed with fine, gray and yellow hairs (fig. 132). There are also yellowish stripes 
on the thorax and orange-yellow markings on the wing covers. Full-grown larvae 
are creamy white and about 30 mm long. Adults appear during the summer, feed on 
the bark of young twigs, and deposit their eggs in small slits cut in the bark, usually 
in the middle third of the tree. The larvae bore into the inner bark and sapwood 
where they later spend the winter. In the spring, they bore into the sapwood and 
heartwood and feed there until they are mature. Attacked trees are characterized by 
the presence of swollen scars and holes in the trunk and larger branches. Each larva 
bores an opening out to and through the bark through which frass is expelled and 
sap exudes. Wet areas around these holes blacken and appear varnished. The life 
cycle requires 3 to 5 years in the North and 2 years in the Deep South. The usual 
time is 3 years for most of its range. In the North, the second winter is spent as a 
mature larva in a cell at the end of its tunnel (98/). 
Small trees are occasionally killed by larvae girdling beneath the bark. Larger 
trees are seldom killed outright, but the large larval tunnels make them susceptible 
to windbreakage. They literally may be riddled with tunnels. Larval openings and 
tunnels serve as openings for various rots, decays, and other injurious insects which 
may kill the tree or degrade the lumber (878). Poplar plantations may be ruined and 
valuable shade trees severely damaged. Damage in forest stands also may be 
severe. In the Lake States, successful attacks appear to be concentrated in indi- 
vidual trees or small groups of trees unevenly distributed throughout the stand. 
These trees, commonly known as brood trees, are usually the larger, faster growing 
296 
