winding and usually oval in cross section. Eventually, they terminate in elongated 
pupal cells that are connected to the surface by short, oval exit holes. Charac- 
teristically, the mines are usually packed tightly with layers of sawdustlike borings 
and pellets and their walls are scarred with fine, transverse lines. Many wood- 
boring species spend the winter as adults in pupal cells. A few overwinter in the 
larval stage. The life cycle usually requires | to 2 years, but in certain species it 
takes many years. 
Acmaeodera pulchella (Herbst), the flatheaded baldcypress sapwood borer, 
breeds in baldcypress in Eastern and Southern States. The adult is blue-black to 
blackish and about 6 to 10 mm long. In some individuals the thorax is dull bronze 
and the wing covers and outer angles of the thorax are marked with spots and 
patches of waxy yellow. Full-grown larvae are about 13 mm long and the pro- 
thoracic plates are marked by brownish median grooves or lines. The sapwood of 
dead and dying baldcypress trees and recently cut baldcypress logs is subject to 
severe attack and damage. The removal of unseasoned logs from the woods before 
the adults fly in the spring, or girdling trees in the fall that are to be felled in the 
spring, should aid in the reduction of damage. 
The twolined chestnut borer, Agrilus bilineatus (Weber), occurs in southern 
Canada and throughout the Eastern United States. It breeds in various hardwoods, 
preferably chestnut and several of the oaks (348). Trees weakened by drought or 
defoliation, and trees with low root starch (/244) are usually attacked. Adults are 6 
to 12 mm long, subcylindrical, and black with a more or less greenish tinge. The 
sides of the thorax and elytra are clothed with light golden-yellow pubescence, and 
each elytron is marked with a stripe of the same color. The larva is slender, 
considerably flattened, about 25 mm long, and has two spines at the posterior end. 
Winter is spent in the final (fourth) instar in pupal cells constructed in the outer 
layers of the sapwood and sometimes in the bark (249). In the spring, the adults 
emerge through characteristic D-shaped holes in the bark. Eggs are deposited on 
the bark in late spring or early summer. Young larvae bore directly through the bark 
to the phloem. There they excavate winding mines in the inner bark and outer wood 
of the main trunk and larger branches. These mines run back and forth in all 
directions (fig. 119), and in the event of heavy attack, they girdle and kill the trees. 
Attacks usually begin in the tops of trees and are extended downward as the trees 
continue to weaken (5/0). 
Control under forest conditions is usually impractical. A chalcid wasp, Pha- 
sgonophora sulcata Westwood, is the beetle’s primary parasite, accounting for 10 
percent of the host in Wisconsin (5//). Except for management practices that 
maintain or promote tree vigor, such as watering and fertilizing valuable shade 
trees, there is little that can be done to protect trees from attack. 
The bronze birch borer, A. anxius Gory, apparently occurs throughout most of 
the range of birch in Canada and the United States. Various birches, especially 
paper and yellow, are preferred hosts. The adult is deep green-bronze and about the 
Same size and shape as the adult of the twolined chestnut borer. There are coppery 
reflections on the front of the pronotum; the front of the head is greenish in the male 
and copper-bronze in the female. Full-grown larvae are slender, flattened, about 25 
mm long, and have two spines at the posterior end. 
Adults begin to emerge in late May or early June and continue until August, 
depending on locality, and they feed on leaves for about 3 weeks before egg laying 
begins. Eggs are deposited singly or in small groups beneath loose curls of bark and 
in cracks and crevices in the bark, mostly on unshaded parts of the tree. Young 
PAT 
