Sugar Maple Borer - Glycobius speciosus is a long-horned beetle in the Cerambycidae that can cause serious defects in sugar maple, Acer saccharum. The beetle has a 2 year life cycle. Many eggs are deposited on the bark and many beetles start their journey into the tree, but few complete the cycle. The beetles that do complete the cycle are usually enough to cause serious defects due to discolored and decayed wood and twisted grain. (See “Injury”) The beetles usually infest trees in clusters. A great gradation of wounds are caused by the boring grubs. Beetles that die young only score the cambium. Some beetles start to bore into the wood, and then they die or are killed by birds or other agents. The tree responds to all of those wounds and a great variety of discolored streaks result. It would be difficult to find the wound in some of the small columns. The beetles that complete the cycle bore in an upward spiraling path. The beetles in the Cerambicidae keep their galleries free of frass-digested and expelled wood. Seldom do 2 beetles bore into each other, but it does happen. Beetles may also girdle trees. The defects seldom develop far beyond the galleries. The defects are commonly called mineral streaks.
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