Author: Eric Day, Virginia Tech
The common pine shoot beetle Tomicus piniperda (syn. Myelophilus piniperda) is in the same family as bark beetles and resemble bark beetles in appearance with their cylindrical shape. The adults are black or dark brown, 3-5 mm long. The larvae have a dark brown head and creamy white body, are legless, and can be up to 6 mm long. The primary host species is Scots Pine, but it will also use many other pine species, and rarely larch and spruce (Davies & King 1977).
The pine shoot beetle is native to most of Europe and Asia away from the far south, and is one of the most damaging insect pests in pine forests in northern regions. It is also now found in the United States from Illinois to Vermont and south to Virginia. It is thought to have come to the United States with wood pallets, dunnage, and shipping containers arriving on ships coming into the Great Lakes ports. It was first recorded in Ohio in 1992 and was quickly found in other states bordering the Great Lakes.
Adults overwinter in the shoots or on the bark of pine trees. The beetles exit the overwintering site and begin flying about when the temperature reaches or exceeds 12°C. The first flight usually takes place in late winter or early spring. Adults lay eggs on stumps, logs, and dying Scots and related pines, excavating a brood gallery, which is up to 25 cm long and parallel to the wood grain. The larvae feed under the bark and make small side tunnels from the brood gallery. The immature stage usually lasts from April until June. The larvae pupate under the bark and the adults emerge throughout the summer. Adults can fly several kilometres in search of new hosts and there is one generation per year.
Type of Damage
They feed on several pine species, most commonly Scots Pine, and less often Eastern White Pine. The newly emerged beetles damage live shoots of pines in the summer to late winter; this is called "maturation feeding" as they are not laying eggs at this time. During maturation feeding the beetle makes clean tunnels in the pith inside live shoots, commonly attacking the stronger shoots at the tops of young trees, which results in deformed crowns with poor stem straightness. The damaged shoots turn yellow, then brown and are easily contrasted against the remaining green foliage.
Chemical control is usually not necessary.
Removing dead and dying Scots Pines will remove breeding sites and reduce the attractiveness of plantations to beetles that might be in their vicinity. This beetle is not likely to become a problem on garden trees.
By law, all counties that have records for pine shoot beetles must be under quarantine. The quarantine requires that all commercial growers of Christmas trees to be under a compliance agreement with the Virginia Department of Agriculture and Consumer Services (VDACS).
- All dead and dying trees to be removed from the Christmas tree farm. These potential brood trees must be burned, chipped, or buried under at least 30 cm of soil.
- Cut stumps flush (within 2.5 cm) to the ground during or just after harvest. Spray the exposed surface of stumps with an approved insecticide as listed in the Pest Management Guide just before flight of overwintering beetles, January to mid-February, depending on the location (this is the same timing and method used to treat pales weevil).
- Pine species must be visually scouted for infested shoots between July and October. Infested shoots, if found, must be removed and destroyed by burning or burying.
- Pine logs must be used as trap or sentinel logs. Logs must be in place by January and checked once the daytime temperature exceeds 10°C. Logs must be removed between 1-20 April by burning or burying.
- Trees only need to be chemically treated if the pine shoot beetle is found on the farm or within 1 km.
- Pertinent records include the number of trees scouted, scouting dates, sanitation treatments conducted, trap log activities, and insecticide usage. A sample form will be provided for use.
- Nursery inspectors will work with growers in infested counties to clarify any questions about the compliance agreement.
- In Virginia call (757) 786-3515 to arrange to have a nursery inspector visit your farm.
- Davies, J. M. & King, C. J. (1977). Pine Shoot Beetles. Forestry Commission Leaflet 3. HMSO, London. ISBN 0-11-710219-9
- Day, E. Pine shoot beetle. Publication Number 444-291, Revised December 2005.