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What do pine trees infested with pine beetles look like?

Updated February 21, 2017

A handful of beetle species attack and kill pine trees, including the southern pine beetle (Dendroctonus frontalis Zimmermann) and the mountain pine beetle (Dendroctonus ponderosae). Although the beetles may vary, infested pine trees share similar symptoms.

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Pitch Tubes

Adult beetles burrow into the pine's bark to lay eggs. The tree produces sap as a response, and the oozing sap hardens into popcorn-shaped nodules called pitch tubes. Fresh pitch tubes are soft and pale or rose-white. The nodules harden as they age, eventually turning brittle and yellow. An infested tree may show multiple pitch tubes or, in drought-stricken areas, none at all.

Bark Damage

Larvae feed underneath the bark. Red-tinged dust from the burrowing larvae powders the tree and the adjacent ground, and the bark begins to loosen and flake. The larvae leave serpentine paths underneath the bark and, as they mature, produce exit holes. The pine tree's inner wood often has a blue fungus.

Needle Color

Newly infested trees remain green, but the needles begin to yellow within three to four weeks. In some cases, the needles may remain green through the winter and only show damage in spring. The pine tree's entire crown fades, yellows and eventually turns a red-brown as the pine dies.

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About the Author

Kimberly Richardson has been writing since 1995. She has written successful grants for local schools as well as articles for various websites, specializing in garden-related topics. Richardson holds a Bachelor of Arts in English and is enrolled in her local Master Gardener program.

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