Watch out for unwelcome insects

An invasive organism is an unwelcome pest in any type of ecosystem, be it forest, field, wetland, river, or tidal zone. They are not native to an area and may be better able to survive than native species, often because these organisms are less likely to have natural predators and the food sources that they utilize have not evolved to defend themselves against the non-native pests.

In 2011, the U.S. Forest Service and The Nature Conservancy participated in a study which concluded that the cost of non-native, wood-boring insects on local governments in the United States is around 1.7 billion dollars a year. In addition, these insects, like the Asian Longhorned Beetle and the Emerald Ash Borer, account for about 830 million dollars in lost residential property values a year.

In New Hampshire, with more than 80 percent of our state being forested and forest products accounting for around 4 percent of our gross state product, pests that infest and decimate our forests are of particular concern.

These pests can damage our economy and our sense of place. If we lose significant tracts of trees that people associate with the picturesque forested New Hampshire landscape, tourism is also sure to suffer.

Some of the invasive insects that we need to be watchful for in New Hampshire include, the Winter Moth, the Emerald Ash Borer, Red Pine Scale, White Pine Blister Rust, Elongate Hemlock Scale, and the Asian Longhorned Beetle. Visit to learn more about any of these and other invasive insects, including their life-cycle and how you can help detect and discourage them from inhabiting your property and community.

The Asian Longhorned Beetle has not yet been found in New Hampshire, but it has been identified in nearby states. This pest feeds on hardwood trees and has a particular fondness for maple, which should make us all fear for our pancakes. The beetle larvae tunnel under the tree bark, interrupting the flow of nutrients from the roots to the canopy.

When larvae become adults, they chew their way out of the host tree through round dime sized exit holes and push out a sawdust-like material. Adults also eat the leaves of host trees.

The beetles can be seen in their adult form from July to October. Check pool filters and skimmer debris for the beetles. The beetles are black and glossy with white spots and are around one inch long, with very long black and white antennae and bluish-white legs. The antennae are as long as the body in females and twice as long as the body in the males.

Another invasive insect that spends the majority of its life cycle under tree bark is the Emerald Ash Borer. This insect has been detected in four communities in NH in 2013 and 2014. It infests white, green, and black ash trees. The larvae feed under the bark of ash trees and create S-shaped tracks under the bark. Emerald Ash Borers emerge as adults in late April or May through a D-shaped exit hole. Unfortunately, the holes are usually too high in the tree to see from the ground, but a close inspection of downed trees can help you spot the exit holes.

Emerald Ash Borer adults are green and metallic and they can be seen from June to September. The branches of infested trees eventually die, and the tree canopies will begin to look sparse. You may have noted some purple boxes hanging from ash trees, these are intended to help identify the presence of Emerald Ash Borer. Wood peckers feed on the Emerald Ash Borer, so if you notice more wood peckers visiting your ash trees than usual, you may want to investigate.

Winter Moth is another major pest found in Maine and Massachusetts, but we thankfully do not have confirmed infestations in New Hampshire at this time. Winter moth caterpillars eat the leaves of hardwood species. At this time of year, the caterpillars are pupating in the soil, so they are nearly impossible to find. However, keep a watchful eye for the adults to emerge in late November. Males are drab-colored with wings that are fringed with small hairs on the hind edge. The wings have a bottom row of dark banding near the tip that looks like hash marks. The female has such small gray wings that she appears almost wingless. The female can be seen climbing up hardwood tree trunks. Winter moths can remain active into January.

One other pest to be on the look out for is the Hemlock Wooly Adelgid. This pest infests hemlock trees. It is much smaller than some other insects, only about the size of a pin head, and is covered with a woolly material. It is spread by wind, birds, and deer. Humans can also move it in mulch and other forest products. A dry white wooly substance on young twigs, not the needles, is a symptom of an infestation.

There are ways you can help reduce the likelihood of an infestation in Bedford.

Firstly, never transport firewood from out of town. Some of these pests can hitch a ride on wood and infest new trees and forests.

Also, keep a watchful eye out for these insects in your own yard and around Bedford. If you see an insect that you suspect could be one of these invasives, take photos, freeze the insect in a plastic container and report your finding on You can also report infested trees on this site and learn more about other pests to watch out for in New Hampshire.

The next time you are out for a forest stroll, keep a vigilant eye on the trees, one aware person can detect an infestation and prevent it from eliminating a valuable resource or radically changing the landscape that has drawn us all to live in one of the most forested states.