Common Pine Shoot Beetle
FACTS, IDENTIFICATION & CONTROL
Common pine shoot beetles closely resemble both the southern pine beetle and black turpentine beetle. They can be distinguished from other members of the genus by their smooth second elytral interval. Adult beetles are 1 mm in length, cylinder-shaped and dark brown or black and shiny in color. The larvae are white grubs with brown heads (which is typical of many beetle species) that can grow up to 5 mm in length. Eggs and larvae can be found under the bark of weak trees or stumps.
BEHAVIOR, DIET & HABITS
Common pine shoot beetles are known for infesting pine timber in forests, railway stations, timber yards and other wood storage areas. They spread into surrounding pine forests if no preventative measures are taken. Forest fires, windstorms and defoliating insects create favorable conditions for the breeding of pine shoot beetles, which leads to shoot damage in the pine forests.
Pine shoot beetles live in a tree’s trunk and crown but attack the tree’s shoots, which are its small branch or sprout portions, making the tree appear dramatically smaller in height and diameter. Their preferred host is the Scotch pine. Pine shoot beetles prefer slightly cooler climates, preferably 50 to 55 degrees Fahrenheit.
Adult pine shoot beetles typically overwinter in twigs or galleries located at the base of a tree. Maturation from egg to adult takes about three months and adults typically emerge in June. Recently emerged adults move up to the tree’s crown to feed on growing tips throughout the summer. Adults then move back into the trunks in order to construct additional galleries and lay a second batch of eggs.
Soon after laying eggs, the adults surface and die. The larvae then appear and feed in separate galleries from April to June. In May or June, the larvae pupate and a new generation emerges through the bark and attaches onto pine trees’ new shoots. The common pine shoot beetles move into the soil or the base of pine trees to overwinter. Adults can generally overwinter in shoots during warmer weather, but they move under the bark at the base of trees when colder weather approaches.
SIGNS OF A COMMON PINE SHOOT BEETLE INFESTATION
To detect signs of an infestation, look for the following: dieback, yellowing and bored-out shoots littering the ground under infested trees. The damage may resemble what is sometimes caused by pine tip moths, so damage should be carefully examined. Adults create exit and entrance holes about 2 to 3 mm in size near the broken end of shoots. The first and second year shoots begin yellowing and eventually turn red in the early summer.
Since first invading Canada and the United States in the late 1990s, pine shoot beetles have caused extensive damage. There is no proven way to successfully manage these pests, but some management techniques attempted in Europe include the debarking of cut timber and precisely timing any cutting operations.