NISAW: Emerging Invasive Insect Threats
Be on the lookout for these two destructive invasive insects.
Two invasive insects are spreading in the United States; as luck would have it, neither has been found to be established in Maine. But that could change any day, so please be aware of these pests and report any suspicious sightings to help our efforts to manage them.
 By now, most people have heard about the spotted lanternfly (SLF) – the planthopper that looks like a moth. This species was spotted approximately 10 years ago in Pennsylvania, who tried very hard to contain this new-to-US insect. But this insect can easily move around - mostly with the help of humans. It is now established in 17 states, and luckily Maine isn’t one of them... yet.
The concern with spotted lanternfly is that it feeds on hundreds of different crops and trees. Adults and nymphs insert their straw-like mouthparts into woody stems and suck out sap, in turn causing an excretion of honeydew that allows the growth of sooty mold. Not only is the plant weakened by the feeding, but the sooty mold blocks photosynthesis required for plants to stay alive. Preferred SLF hosts are grape, hops, maple, walnut, and the invasive tree-of-heaven (Ailanthus altissima).
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The Maine Department of Agriculture, Conservation and Forestry has received reports of dead SLF adults being found in warehouses, and in imports of plant material and packaged products, and of egg masses being found on some imported nursery stock. Even live adult spotted lanternflies were found on a cruise ship in Portland last year. So far, no populations of SLF are known to be established in Maine. But, it's ability to move on vehicles, products, and nursery stock make our days numbered.
So, please become familiar with this insect and let us know if you *spot* the spotted lanternfly in Maine. Send a message with photos to [email protected]
Adult spotted lanternflies. Photos by MJ Raupp, Emelie Swackhamer (PSU), Heather Leach (PSU), Richard Garner (Bugwood.org)
The other emerging invasive pest issue that may not be as well-known is box tree moth (a moth that looks like a moth!). This pest was first discovered in New York in 2021 and has subsequently been found in five other states (Delaware, Massachusetts, Michigan, Ohio, and Pennsylvania).
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Although this moth is a strong flier, it mostly moves around to new areas as eggs and caterpillars on nursery stock. Unlike spotted lanternfly, the box tree moth seems to prefer only one plant – boxwoods (Buxus spp.).
There is a federal quarantine in place to prevent movement of infested boxwoods into other states, but eggs and caterpillars can be missed. It’s important to check your boxwoods carefully for signs of this new invasive insect. If you suspect you have box tree moth, immediately contact [email protected]
Clockwise from top left: adult box tree moth (Ian Redding), box tree moth caterpillar feeding and leaving tell-tale silk webbing (Ilya Mityushev), infested boxwood shrubs in Ohio (Joe Boggs), characteristic damage from feeding caterpillars (Ferenc Lakatos), a "hibernaculum" - 3 boxwood leaves stitched together by an early stage overwintering caterpillar (DACF).
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