By and large, Spotted Lanternfly does not destroy trees and shrubs, and any damage they may cause will be minimal and not easily noticed (and not very significant to long-term plant health). An exception would be certain agricultural settings, like vineyards, where the insect can cause problems with harvest quality/quantity if the vineyard is not otherwise spraying their grapevines for other insect issues. (Because such sprays will likely kill lanternfly in the process.)

When this insect was first detected in the U.S. ten years ago, agriculture departments were advising that people squish them so they would not spread as easily. Not enough information was known yet about what level of threat they posed to forests and agriculture (and by extension, home landscapes as well), so there was an abundance of caution and a public awareness campaign to both track and slow their spread. Now that researchers have had a chance to study the insects and observe their impacts, we know that they are fortunately much less of an acute threat than was first feared, and predators like birds and other insects and spiders are starting to eat them. While the Maryland Department of Agriculture would still like the public to report sightings (submission form link on the web page above) and squish the insects when feasible, that is not going to stifle their spread at this point, as most of Maryland (and several other states in the region) now has this insect present to some degree or another. Too many lanternflies can be out of reach in tree canopies for any physical or chemical intervention to accomplish much.

Home and community gardens do not need to be protected using insecticide or other means, though once the insects are correctly identified (as a few local insects can look similar), lanternflies can still be squished as people see fit (though it won't make much of a dent in the local population). No insecticide is specific to lanternfly; all ingredients bear some level of risk to other insects or wildlife, including beneficial predators and pollinators. When sprayed, lanternfly tends to jump (or as adults, fly) away, as they are usually wary and easily disturbed, meaning that any contact-type of insecticide won't work very well if they don't get thoroughly coated by the spray. Any spray whose residues do remain active for longer (like the chemical class called pyrethroids) runs the greater risk of harm to other animals.

If aggregations of lanternfly are too much of a nuisance, this time of year they can be squirted with plain water from a hose, swept off of trunks or siding, or netting fairly easily during cool mornings and evenings. Like all insects, they become sluggish in movement when chilled. They would then be easier to gather and squish if you wanted to get rid of some without pesticides. An alternative to squishing would be to dump them into a tub of soapy water to drown. The adult lanternflies will be dead once we experience one or more frosts/freezes.

There is no single list of vulnerable plant species because these are generalist insects, capable of feeding on a wide variety of plants (one reason for the initial ag. department concern). They do favor Tree of Heaven (Ailanthus), an invasive species from the insect's original habitat, and a couple local native trees like Black Walnut and Red Maple. However, we have yet to learn of any circumstances where either walnuts, maples, or other trees succumbed to lanternfly damage. Tree decline tends to occur over months or even years, and any tree or shrub that dies with lanternflies associated with it probably was ailing from an unrelated issue that began some time ago, and a certified arborist can help with tree diagnosis.

Miri

Thanks very much for this informative response.

You're welcome.

You're welcome. We are happy to help.