Now Is the Time to Address the Invasive Spotted Lanternfly & Tree of Heaven

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Many people in the US may just now be hearing about the invasive spotted lantern fly and its tree of heaven host plant. For those of us on the East Coast, they are hard to ignore and causing massive economic and ecological devastation. New York state estimates hundreds of millions of dollars in economic damage to the state, with billions of dollars of potential impact on a national level if allowed to spread. Fall is the best time to address the problem, and now is the best time to slow the spread into areas not already infested. While some people may not like the idea of killing bugs or trees, doing nothing could lead to far more destruction.

The infestation started in Pennsylvania, theorized to have come over on a shipment of imported landscaping stone. As such, Pennsylvania is ahead on the learning curve, with the Penn State Extension having extensive resources regarding the spotted lanternfly and how to manage the infestation.

My first experience with the spotted lanternfly was also in Pennsylvania, picking apples on a trip with friends. The orchard we visited that once prided itself on being as natural and organic as possible was infested and resorted to extreme measures to try to salvage the crop, dousing mold covered trees with pesticide and throwing out piles of fruit unsuitable for human consumption. I felt like this would be a big problem if it spread, which it did quickly.

Soon we had them in NYC. When walking through nearby Forest Park, their increasing numbers were obvious. We were encouraged to squish them if we saw them, and many of us did. While the original intention was to eradicate the invasive pest, the goal now is to try to control the infestation and slow the spread, while measures are developed to manage the invasive insect. Even so, much of the East Coast is now infested.

What’s the Problem and How Did It Get So Bad?

The spotted lanternfly is an insect native to Asia, where natural predators keep it under control. Once it reaches adulthood, the spotted lanternfly spreads to a range of trees and plants, piercing the bark to consume sap, weakening the plant and excreting honeydew. That sticky honeydew ends up creating black mold, which can cause even more damage, especially for fruit trees. The lanternfly can kill grape vines, hops, and saplings, while weakening several species of fruit trees and sugar maple…. In other words, if you like to drink or eat fruit (especially local, organic fruit), this little bug is not your friend.

However, the infrastructure for the infestation was allowed to spread long before the insect arrived. The invasive tree of heaven (Ailanthus altissima) is the host plant of the spotted lanternfly and was introduced over a century ago as an ornamental plant. It was planted for fast growth and the ability to fill in areas quickly. However, it spread out of control.

The tree tends to grow along the edge of wooded areas. Its winged seeds (samara) are carried by the wind. In addition, the root system tends to send up new shoots as it extends out. If you simply cut it down, multiple trees will pop up in its place. As such, places where brush is periodically cleared, like the sides of roads, rivers, and rail tracks, tend to be heavily infested with the tree. This essentially creates an expressway for the lanternfly to spread.

The tree of heaven’s root system tends to be very shallow. This helps the tree to spread, as well as damaging foundations, roads, and sidewalks. Combined with the weak wood, larger trees can be susceptible to toppling over, damaging property. The roots also send out toxins that prevent the growth of other plants. However, the plant’s toxins pose a larger problem.

In their initial stages, spotted lanternflies tend to rely on the tree of heaven. It has thin-bark and is their native host plant in Asia. Nymphs feeding on the tree of heaven are far more likely to reach adulthood, then they go on to attack a broader range of plants. When feeding on the tree of heaven, they sequester toxins that deter many potential predators native to North America. This makes efforts to manage the spotted lanternfly more difficult. There has been discussion about introducing predators from Asia, but that could create unintended consequences.

Doing Something Now Can Help Prevent More Damage Later

Due to the economic consequences of uncontrolled proliferation of the spotted lanternfly, more environmentally destructive means are likely to be used if the spread is not controlled. Even if your area is not currently infested, there are steps you can take now to address the problem.

Regardless of where you live, one of the best steps is to remove the invasive host plant. I would even consider this in Europe. Europe does not yet have a lanternfly infestation. However, I recently noticed that the tree of heaven is prolific along the river in Mainz. A lanternfly infestation could spread rapidly, potentially decimating surrounding vineyards in Germany and France. The Tree of Heaven can be identified by compound leaves (multiple leaflets on the same leaf stem), with each leaflet having a long, pointed shape, smooth sides, and bumps at the bottom. I think they look like spearheads. You can also tell them by their bitter smell, which I would describe as a mixture of boiled peanut shells and rotten garlic. A good place to start removal is on your own property. If looking to public property, talk to the parks department or state before you start pulling them … some places might not be encouraging it yet.

The most ecologically friendly way to remove the tree of heaven is to pull seedlings and young trees manually, removing the roots. The shallow root structure, tending to go off at a right angle a little under the surface, means that you can pull significantly larger trees out of the ground than you might think. I like to go after a rainstorm, when the soil is loosened up a bit. If you are pulling, sometimes you can get several shoots attached to the same root structure. There is still a chance that some root will remain and send up new shoots, but persistence pays off.

Larger trees need to be poisoned with a systemic herbicide like glyphosate (aka Roundup) or triclopyr before being cut down. This should happen in late summer/early fall, when sap is heading down to the roots for winter. Otherwise, the tree will send up a multitude of new shoots from the remaining roots. “Slash and squirt” is the most controlled and environmentally friendly means of application, where a cut is made into the bark of the tree and the herbicide is applied to the cut. Otherwise, foliar application (sprayed on the leaves) is faster, and more likely to be done at large scale. However, this is less targeted, with more impact on neighboring plants and runoff into the environment.

If you are in an infested area and see a lanternfly, squish it. In fall, they are at their largest and easiest to see. They cannot fly far and tire after a few jumps, even if you initially miss. When going through the park, we tend to carry leather fly swatters. It might make you look like you are heading to an S&M convention, but they work well on curved trees and are far more durable than the cheap plastic fly swatter you probably have at home. If the majority of tree of heaven are removed from an area, the lanternflies will concentrate on the remaining trees, and specialized traps can be used to catch them as they crawl up the trunk, while avoiding other animals. However, they tend to be moderately effective. If lanternflies take over an area, pesticides are more likely to be broadly applied, killing both the lanternflies and other beneficial insects. The best option currently available is to try to squish them.

Fall is also egg laying season. Egg masses tend to look like a smear of mud, which makes them hard to detect. If you are driving through the East Coast of the United States this fall, be sure to check for stowaways and egg masses. Wash your car thoroughly, including the wheel wells, ideally before heading home. If you see an egg mass on a tree or vertical surface, the best option is to try to scrape it into a jar of rubbing alcohol to kill the eggs. Otherwise, crushing the eggs can work.

However, when addressing the invasive species, be sure to take care of yourself. If pulling them up manually, remember to lift with your legs, not your back. Some people have also claimed to have had reactions to the plant. I have not had any reaction, but if you tend to get allergies, gardening gloves might be useful. Also, when walking through any wooded area, keep a lookout for ticks. In addition, while the lanternflies do not bite or sting, the excreted honeydew tends to attract yellowjacket wasps, so be careful when swatting. If applying herbicide, remember to use the recommended protective gear.

Beyond actively taking part in the management, people can also help by reporting invasive species to organizations managing the infestation. Organizations like NY iMapInvasives help to keep track of the infestation, and many other states have similar resources.

Overall, the infestation is likely to spread. However, slowing the spread can give the people managing the infestation time to develop solutions. And it helps to reduce the economic and environmental damage of the insect and the measures used to address it. Each individual may seem to only be doing a small part. But if everybody does something, we can have a significant impact.