Quick Facts

  • Adult pine shoot beetles are 3 to 5 mm long
  • Brown or black and cylindrical
  • Legless larvae are about 5 mm long with a white body and brown head
  • Complete only one life cycle per year
  • Spend the winter months inside the thick bark at the base of living pine trees

Species Facts:

The Pine Shoot Beetle, Tomicus piniperda L., a serious foreign pest of pines, was discovered at a Christmas tree farm near Cleveland, OH, in July 1992. A native of Europe, the beetle attacks new shoots of pine trees, stunting the growth of the trees. The pine shoot beetle may also attack stressed pine trees by breeding under the bark at the base of the trees. The beetles can cause severe decline in the health of the trees, and in some cases, kill the trees when high populations exist.

The U.S. Department of Agriculture's (USDA) Animal and Plant Health Inspection Service (APHIS) has taken steps to prevent this insect from moving to major pine tree-production areas. To date, APHIS, in cooperation with State officials, has quarantined counties in Illinois, Indiana, Maryland, Michigan, New Hampshire, New York, Ohio, Pennsylvania, Vermont, West Virginia, and Wisconsin. Surveys are completed each year to monitor the natural spread and artificial movement of the pine shoot beetle.

Through detection surveys, the beetle has been found in pine tree-production areas including Christmas tree farms and nurseries. Pine shoot beetle has also been detected in mature pine stands and areas surrounding mill yards that process pine logs. The beetle prefers Scotch pine, but it will feed and reproduce on most, if not all, species of pine.

Natural dispersal of the pine shoot beetle can occur when the beetles emerge from their overwintering sites. Studies show beetles are capable of dispersing 2 km in the wind. Artificial dispersal to non-infested areas can occur through the movement of infested pine Christmas trees, pine nursery stock, bark mulch, and pine logs.

The beetles become active and leave their overwintering sites in March and April (when temperatures reach 54 °F) to mate and lay eggs in dying or stressed pine trees, pine trees and stumps which have been recently cut, logs, and bark mulch. Adults have been shown to fly several kilometers during this period in search of a suitable host. To create a place to lay their eggs, females bore gallery systems between the inner bark and outer sapwood of the host. Egg galleries are 10 to 25 cm long.

From April to June, larvae feed and mature under the pine bark in separate feeding galleries that are 4 to 9 cm long. When mature, the larvae stop feeding, pupate, and then emerge as adults. From July through October, adults tunnel out through the bark and fly to new or 1-year-old pine shoots to begin maturation feeding. The beetles enter the shoot 15 cm or less from the shoot tip, and move upwards by hollowing out the center of the shoot for a distance of 2.5 to 10 cm.

Affected shoots droop, turn yellow, and eventually fall off during the summer and fall. Feeding adults attack shoots of living pine trees of all sizes, mainly in the upper third of the tree. This is the most destructive stage of the life cycle. When shoot feeding is severe, tree height and diameter growth is reduced. The tree can be weakened to the point where the beetles can attack the trunk of the tree and use it for egg laying.

Portions of this article courtesy of: Animal and Plant Health Inspection Service
Image of a Pine Shoot Beetle (Photo from: www.bugwood.org Credit to: Robert Dzwonkowski)