DURHAM, N.H., February 9, 2017 – Potentially damaging, wood pests in downed trees are wood-inhabiting insects — they survive in trees cut into logs after storms to live for much longer than thought. These likely tree-killing pests live for up to several years following a major weather disturbance, a recent U.S. Forest Service study concluded.
In June 2011, a powerful EF3 tornado tore a 39-mile path through western Massachusetts, damaging or killing thousands of trees. After the storm, Forest Service entomologists conducted a study to determine how long firewood cut from a major disturbance would harbor potentially damaging insects.
“The downed trees full of wood pests provide habitat to many insects over time,” said Kevin Dodds, a Forest Service entomologist and lead author of the study. “This habitat changes over time as the downed trees decay, and generally speaking, the insects that colonize tree material early can often be the most damaging if moved into new environments.”
Such as the Asian longhorned beetle (pictured above) and emerald ash borer pose major threats to forests across the United States and can be easily spread in wood products.
The entomologists collected ash, birch, maple, oak and pine logs from the blow down area and split it into firewood-sized pieces. “Firewood was collected by the third week of April 2012, 2013 and 2014 and placed in rearing barrels after splitting,” reads the study.
Each year they opened the drums and painstakingly inventoried the insects that had emerged from the wood. They kept detailed records of the number, species and year that the insects had emerged, as well as from which type of wood.
Wood Pests…Even Three Years After A Tornado?
The study noted that firewood harvested from the large scale disturbance of wood pests in downed trees fallen in northeastern hardwood forests produced large numbers of insects, even three years after the tornado.
“It was a little surprising that even after three years, we still found insects associated with recently killed trees emerging from firewood,” Dodds added.
Movement Of Firewood Spreads Tree-Killers
Dodd’s discovery adds another note of caution to the movement of firewood and other wood products. The long distance movement of firewood is a major contributor to the spread of tree-killing invasive insects.
“Even years after firewood or logs appear to be safer for transport, they might still be infested with forest-harming insects,” added Dodds.
Eastern Ash Bark Beetle, Or EAB, Has Not Hit The West Coast (Yet)
…however, a January 2017 EAB quarantine map has levels of detection services in place — as far west as Texas — in a new map posted below — since the tree devastation caused out east by EAB causes areas of tree blight deaths.
“Some may believe that older firewood poses less of a threat for moving pests, however, we found that at least at three years out, this material can still harbor damaging insects.”
– Kevin Dodds
U.S. Forest Service entomologist and lead author of the study
Dodds explained that his team wanted to put themselves in the shoes of someone who wanted to cut firewood after a tree needs removal from being blown down. “The goal of the project was to act as if we were cutting or salvaging firewood. If there’s a big disturbance, people and municipalities will clear their properties, often through firewood cutting, over a period of years,” said Dodds.
It turns out that not all of the trees died at the same time following the storm. Some of the damaged trees stayed alive for several years after being blown over. The disturbance happened in year one, but in year three or four there were still insects associated with recently dead trees found in firewood.
In Northern CA, Bark Beetles Are The Number One Invasive Tree Beetle Of Conifers
Tiny bark beetles (pictured above), family Scolytidae, are common pests of conifers (such as pines) and some attack broadleaf trees. Over 600 species occur in the United States and Canada with approximately 200 in California alone.
The most common species infesting pines in urban landscapes and at the wildland-urban interface in California are:
- engraver beetles
- red turpentine beetle, and the
- western pine beetle.
In high-elevation landscapes, such as the Tahoe Basin area or the San Bernardino Mountains,
- the Jeffrey pine beetle and
- mountain pine beetle are also frequent pests of pines.
Serpico Landscaping loves trees. Our Tree Care division of certified SF Bay Area arborists commends the U.S. Forestry Service for their announcement from this study. Summarizing the results, there is a much longer time period after a big storm for safely moving wood due to wood pests in downed trees surviving as hidden parasites.