After I posted this photograph of spotted lanternfly egg masses on Twitter, several people asked me to point out where, exactly, the masses were. I did, but I also thought I’d add these images to my website in case people would like to use them in presentations (to help people prepare for the arrival of the pest in more states). I’ll highlight the egg locations below, but first try to find them. Click on the photograph to view a larger version.
Here is an image that shows the locations.
These photographs were taken on February 28, 2020, at the Morris Arboretum in Chestnut Hill, PA. The river birches in the area had hundreds if not thousands of egg masses.
Spotted lanternflies tend to oviposit on any smooth surface, including man-made objects like buildings, shipping containers, cars, trains, shovels, etc.). They also have the annoying habit of laying egg masses underneath loose bark. There are, sadly, so many ways the insect is annoying.
Below are tips for homeowners who’d like to kill spotted lanternflies (Lycorma delicatula), invasive planthoppers from Asia that use bark-piercing mouthparts to suck out phloem from a wide variety of trees, shrubs, and vines. They can aggregate in the thousands when they find a suitable host plant. An additional reason to dislike them is that they exude a sugary exudate that coats plants and surfaces with a sticky, slippery film that eventually turns black due to fungal growth.
Although it is impossible to eliminate all of the spotted lanternflies from a yard, with a little vigilance you can minimize their numbers and thus protect your favorite trees from being weakened. Below are suggestions on how to kill them at the egg stage (September to March), the nymph stage (April to May), and the adult stage (June to November).
The easiest way to kill large numbers of these insects is to find them at the egg stage and squish them. This can be done by applying enough force with a hard, flat object (stick, trowel, stiff credit card) to create a popping noise as you progress from one side of the case to the other. You should see juices being exuded.
I also think that a mini rolling pin would be ideal, as would the smooth end of a meat-tenderizer mallet (but don’t hurt your trees!). A meat tenderizer is better than a hammer primarily because it better protects the user from the resulting spray of liquid as the eggs are crushed.
PRO-TIP: In late winter and early spring the egg masses becomes brittle, so apply a section of wide tape over the egg case before hitting them. This prevents eggs on the edges from being launched to safety.
If you can’t stomach the sound and the goo, an alternative is to scrape the eggs into a container filled with a fluid such as alcohol or hand sanitizer, or into a container or bag that can be sealed and thrown in the trash. The important consideration here is that simply scraping them off the tree onto the ground will not kill the eggs/larvae that are inside.
There are several challenges to killing them at the egg stage. The first is that the egg masses are covered with a shiny purple/gray substance that tends to weather and blend in with tree bark over time, so finding them is difficult. Here are some photographs that illustrate the variability (click to expand).
Second, the egg masses are often high up in the canopy of a tree, sometimes on thin branches that you’d never be able to reach even if you are a good climber. Third, the adults have a habit of ovipositing in areas that are completely hidden from view, such as underneath a loose piece of bark, behind a seat cushion on the deck, or in a wheel well of a car. There’s just no way to find all the egg cases in a yard.
PRO-TIP: as the egg cases weather the eggs beneath the waxy substance sometimes become more visible. So make a habit of reexamining surfaces in February and March when leaves are not blocking your view. Take a cup of coffee or a glass of wine with you on patrols, to keep your spirits up. As motivation, remember that each egg case has 20-50 eggs, and they are much easier to kill than 20-50 nymphs.
As far as I know, spraying the egg cases with insecticide is not especially effective. A propane torch is likely to do the trick but I wouldn’t recommend that if eggs are attached to a tree or your house.
Here are ways to kill nymphs (followed by details for some):
Attach circle traps to trees
Sticky trap with wire guard
Cordless hand-held vacuum
Pathogenic fungi (?)
Flyswatter: If you are protecting just one tree, insert a pushpin into the trunk so that you have a convenient place to hang the flyswatter.
Sticky traps: The nymphs crawl up and down trees starting in April so you can trap hundreds if you wrap trunks with sticky tape. If you want to go low-tech, duct tape works OK (use push pins to attach) but you’ll need to replace after every rain. You can also buy commercial tapes that are weather resistant. These commercial tapes often have two issues, though. The first is that double-sided tapes will leave a band on your tree forever, so protect the trunk with plastic wrap (underneath) before applying. The second is that some tapes are so sticky that they’ll easily trap birds (and squirrels, snakes, and bats) so you MUST cover the band with chicken wire. Here’s a photograph of a bird trapped on sticky paper in case you think this risk is overblown. Penn State has a good summary of using sticky traps. As does Farm & Dairy.
Cordless stick vacuum: A DustBuster would work fine but the long extension arm of a stick vacuum is ideal for reaching into vegetation. I own a Dyson cordless stick vacuum but there are lots of options (e.g., on Amazon).
Bug-A-Salt rifle: I also don’t own one of these, sadly, so I can’t absolutely guarantee it will work. But I’d be really surprised if they didn’t. I think it would make the daily lanternfly patrol really fun, and everyone in the family would want a turn. You can buy them on the Bug-A-Salt website and on Amazon. Do not buy one if you have children in the house … you can definitely shoot your eye out with these things.
Electric flyswatter: I own one of these and they work really well on large flies so I don’t see why they wouldn’t work on spotted lanternfly nymphs. There are dozens for sale on Amazon. I don’t, however, think they have enough power to kill the adults (I’ll check this summer).
Pathogenic fungi: There are at least two fungi (Beauveria bassiana and Batkoa major) that seem to infect spotted lanternfly, so it might be possible to coat them with a powder or a spray and watch them slowly die. Unfortunately, the experiments on whether this is worthwhile are not yet done (or not yet published), so I can’t guarantee success. But in the wild, these fungi seem to do their thing well. I’m going to buy some Beauveria bassiana from Amazon for the 2020 season, just for giggles. Batkoa major is not yet for sale, I think.
Insecticides: I don’t recommend spraying spotted lanternfly nymphs with insecticides, in part because unlike adults, nymphs tend to spread out everywhere in a yard and are therefore hard to target with contact poisons. Plus a typical homeowner (I include myself) is not in a position to apply pesticides safely and in an environmentally-responsible way. That said, nymphs are susceptible to many insecticides and researchers at Penn State University (and elsewhere) have done experiments to figure out which ones are the best. On a related note, I think homeowners should be wary of pesticide applicators and tree-care companies that offer full-yard treatments à la Mosquito Squad (i.e., fogging yard with pyrethroids several times per summer); that will likely cause bird and firefly decines.
Here’s a photograph of an early-instar nymph. Late-stage nymphs (photograph) have red patches on their backs in addition to the spots.
For all their faults, adult spotted lanternflies at least make themselves easy targets. They are large, distinctive, clump in large groups, and rarely do anything to avoid being killed even when you are squishing their neighbors. Here are some ways to kill them (with details below for some).
Pathogenic fungi (?)
Backpack vacuum: If you are serious about controlling spotted lanternflies, go buy yourself a backpack, battery-powered vacuum that has a large, clear repository. Then you can stroll around your yard in the evening and suck up hundreds if not thousands over a short period of time. Another benefit of the vacuum method is that you won’t leave half-crushed lanternflies all over your prized trees. Note: a backpack leaf mulcher will also do the job but might be tad disgusting. A shop-vac will work in a pinch but is much less convenient.
Leaf vacuum: Maybe something like the Black and Decker 36v Cordless (GWC3600L). I don’t own one of these but they look fun. Amazon carries a lot. Most hardware stores can set you up. Note that most leaf vacuums shred … so be prepared for some goo.
Airsoft gun: Don’t get one of these if you have kids. But if you have a semi-responsible adult who enjoys killing spotted lanternflies, this would be an amazing gift. I see them as especially valuable in killing the adults that are high up in branches, out of the range of your vacuum. Buy only biodegradable pellets, opt for lightest pellets you can find (to minimize tree damage), and wear safety goggles (the pellets ricochet off tree trucks). Note that Airsoft guns are illegal in some areas (e.g., Arkansas, parts of Michigan, Washington D.C., San Francisco, Chicago, NYC). And, of course, you always run the risk of being shot by police even if you are on your own property. To minimize the risk of being shot, DO NOT remove the blaze-orange tip.
Insecticides: Again, I don’t recommend spraying them with insecticides — this is a nuisance insect, not a health threat, and mechanical controls work well. But if you like chemicals, please follow the directions so that pollution of waterways and death of bystander arthropods (and amphibians) are minimized. For more details on which pesticides work, consult the table under “Chemical Control” on this page from Penn State University.
I also don’t recommend that homeowners treat tree-of-heavens (Ailanthus altissima) with systemic insecticides to create bait trees, currently a popular idea. It seems like a perfect solution: because tree of-heaven is their favorite host, you could potentially kill thousands of adults as they arrive to feed on insecticide-laced trees. And it’s touted as being safe for other insects because few other insects eat the foliage (the trees are invasives from Asia). The huge downside, in my opinion, is that many systemic insecticides find their way into nectar and pollen, and thus these bait trees will likely poison large number of pollinators. This downside should be especially worrying to suburban beekeepers because those chemicals could potentially end up in honey. And, more generally, the bulk of systemic insecticides is likely washed into waterways or taken up by nearby plants in your yard.
Dawn soap: This is one of many home remedies that has gone viral but should not have. Detergents pollute waterways and can also damage plants. I.e., there are actually reasons why Dawn soap is not an approved insecticide.
Propane torch: This looks extremely satisfying (see video) but it’s just going to result in forest fires and home losses. Don’t be that guy. If you’re married to that guy, hide the propane tank.
Chinese mantids: Please do not buy mantid egg cases and release in your yard. Chinese mantids are invasive and mainly eat butterflies (even monarchs, even hummingbirds). They are not beneficial insects, despite claims to the contrary on Pinterest.
Just in case you haven’t seen adults before, here are three:
Kill tree-of-heaven trees
Tree-of-heaven (Ailanthus altissima) is the preferred host for spotted lanternfly so if you have one in your yard it will attract thousands of adults from all across your neighborhood. Kill it right now. And don’t worry, it’s an invasive plant and deserves to die. Note that to kill a tree-of-heaven you need to chop it down and treat stump with herbicide (instructions). Alternatively, treat with herbicide, wait, then chop it down. And if you notice tree-of-heaven in your neighborhood, alert the authorities so that it can be destroyed. Below is a photograph of one in Springfield, Pennsylvania. By the way, that building was covered with egg cases. I’d bet that car (with Massachusettsplates) got egged, too.
Similarly, get rid of Amur cork trees (Phellodendron amurense), another invasive tree from Asia that spotted lanternflies adore.
Much of the above is pulled from presentations I made in 2019 to the CRC Watersheds Association and the Scott Arboretum. If you have any questions or suggestions, please contact me. I live in Swarthmore, Pennsylvania, by the way — deep inside the spotted lanternfly quarantine zone, and just 60 minutes from Berks County, PA, where the pest was first imported, circa 2012, on decorative rocks shipped from South Korea.
I’ve posted a few pics of the invasive spotted lanternfly (Lycorma delicatula) on Instagram but thought I’d feature my full collection in a post. The insect is extremely photogenic but it’s also good to let people know what different stages look like so that everyone can kill them. I still need some early-instar pics as well as some showing spotted lanternflies being consumed by parasites and fungi.