Pine Shoot Beetle (Tomicus piniperda (L.))
During a recent conversation with Forestry Consultant Paul Robertson, he indicated that one of the major insect problems on the horizon is the Pine Shoot Beetle. This insect was discovered near Cleveland, Ohio in 1992 and has since spread to five other states (Illinois, Indiana, Michigan, New York and Pennsylvania), and to 23 counties in southern Ontario and two locations in Quebec.
Pine Shoot Beetle.
Like the Dutch Elm Disease and the Asian Longhorned Beetle, it is believed that this insect arrived through imports using wooden crates and pallets. The Canadian Food Inspection Agency (CFIA) has responsibility for introduced pests. CFIA has imposed a quarantine on all known infested counties by restricting movement of pine logs with bark attached, unprocessed bark, Christmas trees and nursery stock. Under the North American Plant Protection Organization, CFIA requires that all imports use only crating and packing material that is kiln dried, fumigated or treated with insecticide.
Life History
From information gleaned from Pest Alert – a U.S. Department of Agriculture pamphlet - Tomicus piniperda has one generation per year. Adults are about the size of a match head, black to dark brown in colour, and cylindrical in shape.
Adult Pine Shoot Beetles.
When warm weather arrives in the spring (7° C-8° C average), the adults fly ½ mile in search of host material for breeding or shoot feeding. Adults attack both healthy and stressed trees. The principal host tree is pine (Austrian Pine, Eastern White Pine, Red Pine, Jack Pine, Scot’s Pine and Mugho Pine), but when population numbers increase adults breed in spruce, fir, and larch. Females mate within the brood chamber and lay eggs in egg galleries 4 to 10 inches in length within the inner bark and outer sapwood of the tree. Eggs are shiny white in colour, oval and about 1mm in length. After hatching, larvae construct horizontal feeding galleries that are approximately 1½ to 3½ inches long. Larvae complete their metamorphosis, pupate, and transform into adults in May and June.
Pine Shoot Beetle egg gallery.
Adults emerge from the bark of the tree by creating small, pin-sized holes; they then fly to the crowns of living, healthy trees and feed until October. One beetle can destroy 1 to 6 shoots per season.
Pine Beetle damage.
Closeup of Pine Beetle damage.
An adult enters an individual shoot in either one-year-old or current season’s growth. They emerge and re-infest other shoots. Adults may overwinter in the fallen shoots in milder climates, but generally spend the winter under bark scales at the base of the tree.
The Ontario Forestry Association – in their November / December issue of "Insect Alert"- highlighted the following points:
What to Look For
- Wilted, drooping, yellowing or fallen shoots.
- Pinhead sized exit holes and boring evidence on the crown stems of trees.
- Adult beetles inside the shoots.
- Shoots with resin-encrusted exit holes.
- Characteristic brood galleries under the bark.
- Shoots with the pith cleanly bored out.
- Eggs, larva and pupae located under the bark of stumps, slash, and cut trees.
- Shoot damage is highest in the upper crown and least in the lower crown of the tree.
Shoot damage in the upper crown of the tree is characteristic of Pine Shoot Beetle damage.
Why all the Fuss?
- No practical treatment exists.
- Tree mortality can occur within two years.
- All native pines in Ontario are at risk, plus Austrian, Mugho and Scot’s Pine.
- An expansion to its present range poses a serious threat to Ontario and Canada’s natural forest ecosystem.
References
Pest Alert. New Introduction - Common Pine Shoot Beetle. U.S. Department of Agriculture, NA - TP - 05/93.
Insect Alert. Pine Shoot Beetle. Ontario Forestry Association, December 1999, pp.2, 10.
Trees Unlimited provides a wide range of forestry consulting services. Founded by Paul Robertson in 1990, Paul and his staff of foresters, botanists and zoologists have over 40 years of experience in Ontario. Paul’s office is located in Welland, Ontario.
