Lanternfly Infestation on Sugar Maple Tree

Question: I've tried a spray of hot water with dawn dishwashing detergent and vinegar and also sprayed Neem.  I had thousands of bugs and now it's more like hundreds. What else can I do? I'm afraid they're destroying my tree.  Thank you.

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied October 11, 2024, 11:26 AM EDT
response: Spotted Lanternfly [SLF] have not been found to seriously harm any home landscape plants or forest trees, and while they can gather on certain species (the invasive Tree-of-Heaven and natives like maples and Black Walnut), they are not causing significant damage. There is no method of control that will eradicate them, and they have spread over the past ten years to nearly all of Maryland and several surrounding states, so even if management efforts in a given yard were successful, it would not last long and the insects can repopulate the area sooner or later. Many will also be far up into a tree canopy and unreachable.  We do not recommend the use of any pesticide to try to manage SLF. Not only will its impacts be quite temporary (if a spray even manages to touch them, since they're fairly jumpy or can fly away), but no ingredient will only kill lanternfly without risking harm to other insects. The longer-lasting the spray residue, the more risk it poses to predators, pollinators, or potentially other wildlife. Lower-toxicity options like horticultural oil (neem being one type) or insecticidal soap can be used, but they won't help much, and thus are probably impractical to spend money and time using. (They must directly coat the insect to work, and given how easily SLF can move away from disturbance, it probably won't hit enough of them to make much of a difference.) An alternative can be to take advantage of their sluggishness on chilly mornings and squish or hose-off (with plain water) SLF from tree trunks, but even so, that still won't keep them from coming back if others are in the area.  Home remedy pesticides are risky to use and either won't work as well as labeled pesticides or can cause worse damage than the pest itself would. We do not recommend using vinegar, household soaps and detergents, or other pesticide alternatives for any insect. Penn State has a good web page (linked above) explaining why they are not a good idea. Hot water, if too near scalding or even above about 120 degrees or so, can harm plants, even if it did work well on the insects.  After a frosty night or two, the adult SLF will all be dead for this year. At that point, any egg masses identified on tree trunks (make sure it's not lichen instead, which is harmless) can be squished or spot-treated with dormant oil at any time during the winter.  If the maple appears to be in decline, other factors are responsible, and a certified arborist or licensed tree expert should evaluate the tree to make a diagnosis and look for sources of tree stress that might be able to be alleviated.  Miri

responder: The Question Asker Replied October 11, 2024, 3:35 PM EDT
response: Thank you very much for all the info, it was very helpful.Yahoo Mail: Search, Organize, Conquer  On Fri, Oct 11, 2024 at 11:26 AM, Ask Extension wrote:

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied October 11, 2024, 3:46 PM EDT
response: You're welcome!