Tag Archives: egg cases

How to kill spotted lanternflies

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.

Lycorma delicatula (spotted lanternfly) showing underwings

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).

Egg cases

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.

Nymphs

Here are ways to kill nymphs (followed by details for some):

  1. Flyswatter
  2. Rolled-up newspaper
  3. Attach circle traps to trees
  4. Sticky trap with wire guard
  5. Cordless hand-held vacuum
  6. Bug-A-Salt rifle
  7. Electric flyswatter
  8. Pathogenic fungi (?)
  9. Insecticides

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.

Circle traps: These involve a little time to make but they look fantastic. Here’s a page that gives detailed instructions.

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.

Adults

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).

  1. Flyswatter
  2. Rolled-up newspaper
  3. Backpack vacuum
  4. Leaf vacuum
  5. Pathogenic fungi (?)
  6. Bug-A-Salt gun
  7. Airsoft gun
  8. Insecticides
  9. Dawn soap
  10. Propane torch
  11. Chinese mantids

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.

PRO-TIP: Buy a Ghostbusters costume for your gullible child and tell them sucking up lanternflies is good practice.

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.

Pathogenic fungi: As I mentioned in the nymph section, Beauveria bassiana is for sale on Amazon. It might not work effectively (or at all) but if you’d like to experiment it might be worth a try. Here’s an adult I found that I think is infected.

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:

Lycorma delicatula (spotted lanternfly) on tree

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 Massachusetts plates) got egged, too.

Similarly, get rid of Amur cork trees (Phellodendron amurense), another invasive tree from Asia that spotted lanternflies adore.

More information

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.

My photographs of spotted lanternflies (flickr).

Latest map of where spotted lanternfly is found in United States, from the New York State Integrated Pest Management Program:

Links

© COLIN PURRINGTON

Identifying mantid egg cases in Pennsylvania

There is one native and three introduced mantid species where I live in Pennsylvania (Delaware County), and I’m trying to get the word out that the invasive ones should be killed when found. This post has photographs of the oothecae along with some brief comments about what makes each species distinctive. At the end of the post I have suggestions on how to put the invasive oothecae to good use.

Carolina mantid (Stagmomantis carolina)

Carolina mantids (the only native species in my area) form relatively smooth, teardrop-shaped oothecae with a central portion that is lightly colored. Often found on tree trunks, rocks, and buildings.

Egg case of Carolina mantid (Stagmomantis carolina)

Chinese mantid (Tenodera sinensis)

Chinese mantid oothecae are typically round (or roundish) roughly textured, and uniform in color. Introduced from Asia, as you probably guessed.

Egg case of Chinese mantid (Tenodera sinensis)

Narrow-winged mantid (Tenodera angustipennis)

Narrow-winged mantid oothecae are usually rather elongate. They are also seem to have red streaks, though the color seems to be most noticeable after they age a few months. Introduced from Asia, too.

Egg case of narrow-winged mantid (Tenodera angustipennis)

European mantis (Mantis religiosa)

I’ve never encountered a European mantis ootheca, so here’s a photograph by Hans Hillewaert (via Wikipedia):

By © Hans Hillewaert, CC BY-SA 4.0

Another common name for the European mantis is praying mantis (not preying mantis).

More ID help

If you need help identifying an ootheca, I highly recommend posting a photograph on iNaturalist. If you post there, feel free to include my iNaturalist username (@colinpurrington) in your caption so that I can have a look. Not only will you get an answer from the iNaturalist community within a day or two, your submission helps scientists track the spread of invasive species.

For an excellent overview of all of these species, please see the Cape May Wildlife Guide’s page on mantids.

What should you do with the non-native oothecae?

Invasive mantids eat butterflies, native bees, honey bees, small birds, and also the native mantid, so when you find egg cases, dispose of them. Here are some suggestions on how to do that:

  • Give them to local bird rehabilitation centers — if local bird rehabilitation center doesn’t know what you’re talking about, inform them that insectivorous birds absolutely adore frozen mantid hatchlings.
  • Give them to a neighbor who has chickens.
  • Give them to a neighbor who has a pet tarantula, snake, lizard, or fish.
  • Put them in a freezer for a week.
  • Step on them.

But whatever you do, do not just relocate oothecae to some nearby field — that just transfers the problem to someplace where you can’t see the problem. I.e., even though you might pride yourself as being a gentle soul that wouldn’t kill a fly, releasing invasive predators will result in monarch butterflies being eaten alive. Don’t be that person. If you simply cannot bring yourself to kill the eggs, ask somebody to help you do the right thing.

But aren’t mantids great for pest control?

Many people (I include myself) grew up being told by highly-educated, seemingly trustworthy adults that mantids are ideal for providing chemical-free pest control in the garden. That view, it turns out, is a myth. Although it’s true that young mantids consume small, pestiferous insects, when mantids are fully grown they tend to camp out on flowers and wait for large butterflies (and even birds). I.e., when a mantid is fully grown it will not even look at an aphid. Mantids are, of course, excellent for controlling butterflies and hummingbirds, just in case you happen to hate those animals.

Some people even believe that mantids can control ticks. They don’t. They are equally ineffective at controlling mosquitoes.