CONCORD, N.H. (AP) — New Hampshire residents with swimming pools are being asked to check their filters for an invasive insect that poses a serious threat to the state’s forests and trees.

The state Division of Forest and Lands asked residents to look for Asian long-horned beetles. The insect was found in trees in Worcester, Massachusetts, in 2008, but experts believe it was there for a decade before that.

The inch-long beetle with long black and white antennae first came in the United States from China and Korea on shipping crates about two decades ago. It has killed hundreds of thousands of trees across the country by boring into the trunks. Foresters have responded by cutting down and removing infested trees.

Forest health specialist Kyle Lombard with the state Division of Forest and Lands says pool filter systems are an inexpensive way to capture insects.

“Pools capture all types of insects in the filter system,” he said. “We’ve learned this method is more effective than insect lures or other trapping systems available to entomologists, so we’re asking folks to look at insects in their filters and take pictures of any beetles resembling invasive forest pests. We’ll identify the insect from the picture.”

Other states, especially in the hardwood-rich regions of the northeast and New England, have used these “citizen scientists” to search for other invasive species such as the emerald ash borer and woolly adelgid. Vermont and New York also have citizen pool-monitoring programs.

The bug can be eradicated: New Jersey and Illinois officials say their states are now free of the tree-killing beetles that were first detected in the U.S. in 1996. More than 20,000 trees were removed in three New Jersey counties as part of its effort to wipe out the bug.

Residents are asked to upload their photos of possible Asian long-horned beetles to the UNH Cooperative Extension website. A good view of the insect’s back is needed to properly identify it. They also should freeze the insect in a plastic container until they hear from officials.