. Annual report of the Agricultural Experiment Station. Cornell University. Agricultural Experiment Station; Agriculture -- New York (State). The Bronze Birch Borer. 141 The borer (Figs. 31 and 35) is a slender, flattened, footless, creamy white grub about three-fourths of an inch long when fully grown. Its small head with dark brown mouth- parts is retracted into the wide, flattened first thoracic segment giving it a flat-headed ap- pearance. The other segments of the body are not so wide, the second and third thoracic being the narrowest. The caudal end of the body ends in two brown, horny,
. Annual report of the Agricultural Experiment Station. Cornell University. Agricultural Experiment Station; Agriculture -- New York (State). The Bronze Birch Borer. 141 The borer (Figs. 31 and 35) is a slender, flattened, footless, creamy white grub about three-fourths of an inch long when fully grown. Its small head with dark brown mouth- parts is retracted into the wide, flattened first thoracic segment giving it a flat-headed ap- pearance. The other segments of the body are not so wide, the second and third thoracic being the narrowest. The caudal end of the body ends in two brown, horny, forceps-like processes with bidentate inner margins. It is this slender creature which is responsible for the killing of the trees. It may be found in autumn by cutting into the trees beneath the rusty-colored spots described on page 140 as occurring on the bark (Fig. 30, fl). These grubs make tortuous or zigzag burrows in the sap- wood around and across the trunk and branches of infested trees, as shown in Figs. 36, a and 32. Work of the Insect. Fig. 31.— The Bronze Birch Borer, a. female beetle; b, first abdominal segtnents of male from below; c, grub or borer. All enlarged about three and one-half times. {From Bull. 18, U. S. Bu- reau of Entomology). This borer attacks white birches of all sizes from nursery trees to stately monarchs more than a quarter of a century old. All parts of the tree, from branches a quarter of an inch in diameter to the main trunk, may be infested. The top branches are always first attacked and killed, then the infestation spreads into the other branches and trunk. The tiny borer, hatching from an egg laid by the adult or beetle on the bark, begins. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Cornell University. Agricultural Experiment Station. Ithaca, N. Y. : The Universi
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