. Bulletin of the Department of Agriculture. Agriculture. ,â BULLETIN No, 437 ,â, Contribution from the Bureau of Entomology ^#t ti L. O. HOWARD, Chief â S^^^'^^J-U. Washington, D. C. PROFESSIONAL PAPER January 16, 1917 FLAT-HEADED BORERS AFFECTING FOREST TREES IN THE UNITED STATES. By H. E. Burke, Specialist in Forest Entomology, Forest Insect Investigations. CONTENTS. Page. Importance of flat-headed borers 1 Food plants 2 Character of the work 2 Life history 2 Seasonal history 2 Special habits 3 Special structural characters 3 Agreement of adult and larval classiflcations. 4 Disting
. Bulletin of the Department of Agriculture. Agriculture. ,â BULLETIN No, 437 ,â, Contribution from the Bureau of Entomology ^#t ti L. O. HOWARD, Chief â S^^^'^^J-U. Washington, D. C. PROFESSIONAL PAPER January 16, 1917 FLAT-HEADED BORERS AFFECTING FOREST TREES IN THE UNITED STATES. By H. E. Burke, Specialist in Forest Entomology, Forest Insect Investigations. CONTENTS. Page. Importance of flat-headed borers 1 Food plants 2 Character of the work 2 Life history 2 Seasonal history 2 Special habits 3 Special structural characters 3 Agreement of adult and larval classiflcations. 4 Distinguishing characters 4 Key to genera of buprestid larva 5 List of genera, distribution, common habits, and host trees 6 References to important literature 8 IMPORTANCE OF FLAT-HEADED BORERS. Flat-headed borers 0)uprestid larvae) are among the most important of the borers infesting forest trees in the United States. Some mine the leaves, one burrows into the cones, a nmnber bore into the inner bark and outer wood of the trunk, branches, and roots, while the majority excavate oval winding "wormholes" throughout the sound or decaying sapwood and heartwood. At present the leaf-miners and the cone-burrower are not common enough to be important. The bark-borers often girdle and kill healthy trees or those injured by fire, floods, droughts, diseases, other insects, or careless lumbering, and at other times weaken trees so that they become easy victims of diseases, other insects, or unfavorable environ- ment. Sometimes when they do not kill the tree outright their work causes dead limbs or twigs, or serious defects, checks, or gum spots to form in the wood, or swollen gaUs to form on the branches. The wood-borers mine the sapwood and heartwood of the trunk, top, and larger branches and thus destroy or seriously injure a large amount of the tree's most valuable product, its timber. Wormholes will cause the finest grade clear lumber to become unfit for the higher grade uses an
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