THE DAVEY INSTITUTE OF TREE SURGERY 
17. TWO-LINED 
CHESINUT BORER 
bFamily BUPRESTIDA. 
Species Agrilus bilineatus 
Weber 
126. This borer is similar 
to the bronze birch borer, 
but is only three-eighths 
inch long and makes a 
smaller burrow. When full 
grown, the burrow is but 
one-quarter inch in dia- 
meter, and is confined 
largely to the bark and Fig. 12. 
cambium layer. In some Exit holes of the bronze birch borer in bark 
cases the larva feeds en- of white birch. After Slingerland. 
tirely within the bark and 
does not enter the wood. 
The larva closely resembles the bronze birch borer, but is only 
three-quarters inch long when full grown. Its work is confined to 
the chestnut, oak, and beech. Some writers think that it will attack 
healthy trees, but in some cases the chestnuts will be badly injured 
or killed, while the oaks near them remain uninjured. The 
evidence strongly indicates that injured trees are the ones attacked. 
127. The larve usually pupate in the bark, and the beetles 
emerge in May and early June. The latter are long and slender, 
about three-eighths inch long and one-third as broad, and of a 
dark brown to black color, with a greenish tinge. The sides of the 
thorax and wing covers are a light golden yellow, with a strip of 
the same color running the full length of each wing cover. 
128. The size of the burrows and the habit of working in all 
parts of the tree, makes this a difficult pest to control. In most 
cases they will have to be left to the control of their natural ene- 
mies, after destroying or barking the badly infested trees, in this 
way destroying the larve before the beetles emerge in May and 
June. By removing the bark and burning it, the insects can be 
killed and the wood saved for other purposes. For valuable trees, 
he repellents can be used during May, June, and the first part of 
Bay to prevent egg laying. The trunk and large limbs can also 
Courtesy Cornell Agricultural Experiment Station. 
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