Two beetles are notorious for infesting pine trees: the mountain pine beetle (MPB), Dendroctonus ponderosae, and the pine shoot beetle, Tomicus piniperda. Ponderosa, Scotch and limber pines are common victims of mountain pine beetle attacks. The presence of larvae and popcorn-shaped resin at the tree's trunk are signs of mountain pine beetle infestation. Native to Europe, pine shoot beetles are found in 19 states east of the Mississippi River. Pine shoot specimens hatch eggs at the base of a pine tree's trunk and feed on new pine shoots.
Pine trees are one of most common evergreen trees in the United States, with over 35 species living within this country's borders. While most pine trees live to be over 100 years old, the lifespan of some specimens falls short due to insect pests. Some pests, such as the pine wood nematode and European pine sawfly, are invasive and have no natural predators. Insecticides are effective in eliminating pine tree pests.
Pine Wood Nematode
Also known as a pine wilt nematode, the pine wood nematode, Bursaphelenchus xylophilus, is native to Japan but was introduced into the United States in the late 20th century. Exotic longhorned beetles carried these pine-wood pests from Japan. The initial symptoms of infestation are wilting and discoloration of the trees' needles as wood nematodes bore into wood for food. Older pine trees are more susceptible to pine wood nematodes than younger specimens.
Tiger Moth Caterpillars
Before they morph into moths, tiger moth caterpillars, Lophocampa spp., wreak havoc on ponderosa and lodgepole pine trees throughout the United States. These caterpillars create tentlike silk mats on the trees' leaves; the mats are the caterpillars' home before they form cocoons. Tiger moth caterpillars feed on the pine trees' needles and branches, causing defoliation and needle discoloration.
Eastern Pine Shoot Borer
Eastern pine shoot borers, Eucosma gloriola, prey on pine tree species such as Austrian, Scotch and the red and white. Adults lay eggs in May and, once the eggs hatch, eastern pine-hoot borer larvae feed on the trees' shoots. The larvae leave the trees during the winter to pupate in nearby soil. Symptoms of a shoot-borer attack are wilting shoots while some shoots turn red. Shoot-borer infestation symptoms usually surface in the fall or winter.
European Pine Sawfly
The European pine sawfly, Neodiprion sertifer, is native to Europe but was introduced into Eastern Canada and New England. The larvae of this flying insect feed on the needles of jack, red, Scotch and Japanese pine trees. Defoliation and needle discoloration are the two primary symptoms of European pine sawfly attacks.
- U.S. Forest Service: Tree List
- Colorado State University Extension: Mountain Pine Beetle
- U.S. Department Of Agriculture Animal And Plant Health Inspection Service: Pine Shoot Beetle
- North Carolina State University College Of Agriculture And Life Sciences: Pine Wood Nematode
- Colorado State University Extension: Tent-Making Caterpillars
- University Of Minnesota Department Of Entomology: Eastern Pine Shoot Borer
- Ohio State University Extension Fact Sheet: European Pine Sawfly