URI Entomologists On Lookout for New Insect Invader

Southern pine beetles eat, kill pitch and red pine trees

By ecoRI News staff

Southern pine beetles are just 2-4 millimeters in size.

Southern pine beetles are just 2-4 millimeters in size.

KINGSTON, R.I. — A team of University of Rhode Island entomologists has set traps at conservation lands throughout western Rhode Island to see if a new tree-killing pest has arrived in the state.

The southern pine beetle, which is native to the southern United States, spread north to New Jersey in 2001, and was discovered in pine forests on Long Island in 2014. This year it has been found in central Connecticut. It’s unclear whether the tiny beetle has arrived in Rhode Island, but if not, scientists say it’s probably on its way.

The blackish beetles are just 2-4 millimeters in size, and they feed under the bark of pine trees, according to URI entomologist Lisa Tewksbury. In their southern range, they infest loblolly and short-leafed pines, but in Connecticut and Long Island they are infesting pitch and red pines.

“Because the beetles are so tiny, they are extremely difficult to see,” said Tewksbury, who is collaborating on the project with the Rhode Island Department of Environmental Management (DEM). “But infected trees respond to the beetles by trying to push out the eggs and larvae with resin. It looks like popcorn-like balls of dried resin mixed with sawdust coming out of the trunk.”

A pine tree trunk infested with southern pine beetles exhibits the diagnostic popcorn-like bits of resin emerging from the tree. (Erich G. Vallery)

A pine tree trunk infested with southern pine beetles exhibits the diagnostic popcorn-like bits of resin emerging from the tree. (Erich G. Vallery)

The larvae of the beetles eat the tree tissue and spread a blue stain fungus, which prevents water uptake in infected trees, according to Tewksbury. Pine beetle infestations can kill a tree in two or three years.

To determine whether the beetles have arrived in Rhode Island, Tewksbury and a team of students have set 10 traps in conservation land in eight communities in western Rhode Island, from Glocester to Charlestown. The traps are a series of 12 black funnels nestled inside each other to look somewhat like a tree trunk and baited with pheromones and pine scent to attract the beetles. Each week, the students collect whatever has been trapped.

No southern pine beetles have yet been discovered. The adult beetles are only active for about six weeks in May and June, so the traps will be removed later this month. If no beetles are caught, Tewksbury said they will probably try again next year.

“If we do catch any, we’ll probably do more extensive trapping and search the area for tree damage,” Tewksbury said. “And then we’ll have to think about developing a management plan to prevent outbreaks.”

Those who observe the popcorn-like balls of resin and sawdust emerging from pitch and/or red pine trees are asked to e-mail a photo to Tewksbury at lisat@uri.edu or call her at 401-874-2750.