Grappling with the spotted lanternfly
Experts say now is the time to kill adults, scrape insect eggs
You’ve seen them. You hate them. And it’s time to kill them.
We’re talking of course about the plague of invasive insects called the spotted lanternfly, whose population has exploded this year in southeast Pennsylvania.
First spotted in western Berks County in 2014, authorities have worked to contain the invasion of the insect which is native to China and Vietnam, but apparently jumped the Pacific on a pallet of stone delivered to Berks County at some point in the last few years.
Since its arrival, it has spread from one to 13 counties in Southeastern Pennsylvania and is making inroads into Virginia, Maryland, Delaware and New Jersey.
But things could be worse, said Evan Corondi, an insect expert with the Berks County Conservation District who gave a presentation on the invader at Pottstown Borough Hall Sept. 20.
In four years, the pest has spread to only seven additional counties. But when the spotted lanternfly arrived in Korea, it had spread across the entire country in three years, he said.
“So I know it can seem like the effort’s not worth it. But it’s working. The things we’re doing to control it are working,” he said to the group of about 90 people who all expressed exasperation with their efforts to eradicate the pest.
One woman — who said she is having eight tree of heaven trees in her yard taken down — said the stink from the insects excrement is terrible. “We haven’t used my back yard all summer. It smells like a urinal.”
Tree of heaven
The lanternfly’s favorite food is the “tree of heaven,” which scientists call ailanthus altissima.
It is itself an invasive species, which is very hard to kill. It is also from Asia and although the spotted lanternfly prefers it, the bug is quickly developing a taste for native North American trees, including fruit trees, valuable hardwoods and grapevines.
When they feed, the lanternfly harms trees in two ways. The first is when it pierces the bark to feed on the nutrients in the layer beneath, robbing the tree of nutrients as well as leaving “weeping wounds” which can attract bees and ants, and also provides other insects or disease access to the tree’s interior.
The second way is what the insect excretes. Called “honeydew,” it is sweet and sticky, but it turns black into what Corondi called “sooty mold.” This smelly substance coats leaves and impedes photosynthesis.
The spotted lanternfly has seven stages of life, beginning with the gray egg masses. The masses which look like a mass of mud, usually vertically oriented on trees, rocks or even the siding of your house.
The adults are currently mating and laying those eggs. Each egg mass contains between 30 to 50 eggs.
They can be hard to spot because when fresh, they are a gray mass, usually laid on an equally gray surface and, “as they dry out, they turn a dull gray,” said Corondi.
“Now is a perfect time to kill the adults,” as they are just starting to lay eggs and fewer adults means fewer egg masses, said Corondi.
However, in a few weeks, the masses will mostly be laid and efforts to combat the pest should turn to scraping them off any surface they are found.
A credit card works best and experts advise having some kind of container or plastic bag to scrape the egg mass into. Once contained, rubbing alcohol will kill the eggs.
An alternative is to crush them,” said Corondi, an exercise he admitted he finds particularly satisfying. “They make this kind of popping sound,” he said with a smile.
As the temperature drops, the adults get more lethargic and are easier to kill, but the first or second frost will kill them anyway.
Eggs will hatch in spring
Sadly, the cold does not kill the eggs, which will be mostly laid by late November and will hatch in the spring into small nymphs about the size of a tick.
They grow to about the size of a dime and take on the striking red and black coloring with white spots.
In this state, the lanternfly is actually susceptible to being sprayed with soapy water as the film from the soap can keep the bugs from breathing through their skin. But once they grow wings, this method seems to work less well.
“I’ve killed hundreds of them with a plan old flyswatter,” bragged one member of the audience.
Spotted lanternfly do not pose a risk to human health, but can affect forest hardwood products worth $16.7 billion in in Pennsylvania.
They like oak, maple and walnut and also affect apple and peach trees, an industry worth more than $119 million. In particular they pose a risk to Pennsylvania’s $944 million nursery and landscape industry.
How do you stop them?
Several kinds of tape, including duct tape with the sticky side facing out, can capture spotted lanternfly at different times of the year because as it turns out, although they are called fly, “they’re not very good flyers,” said Corondi.
They belong to a group of insects called “leaf hoppers” and spread by climbing tall trees or tall buildings and then leap into the wind to travel a long distance.
Of course, they travel the longest distances by hitching rides on our cars, trains and freighters.
That’s why officials urge people to carefully inspect their cars, trucks, trailers, campers and even firewood they are transporting to make sure they are not helping the pest to spread to other areas.
A variety of chemical weapons can be used. Several pesticides work, providing you can get close enough to use them.
But one ingenious strategy Corondi outlined is to use one invasive against the other.
A method called “hack and squirt” uses a type of pesticide called “systemics.” The lanternfly fighter uses a downward stroke to cut some holes in a “tree of heaven” infested with lanternfly and into these holes, apply specific pesticides designed for this function.
The tree with take up the pesticide, which the lanternfly will ingest as it feeds on the tree.
Eliminating all but one or two tree of heaven in a wooded area will force the lanternfly to focus on the remaining trees.
Using the systemic method then allows you to poison many more lanternfly with less poison, as well as eliminating more of the invasive trees.
Unfortunately, because the trees are going dormant for the winter, this kind of assault must wait for spring.
In the meantime, kill as many adults as you can and scrape and destroy as many egg masses as you can find.
This article first appeared as a post in The Digital Notebook blog.
An adult spotted lanternfly on a leaf. The invasive species has spread uncontrolled throughout southeastern
Evan Corondi, an inspect expert with the Berks County Conservation District, displays a branch from another invasive species, the “Tree of Heaven” before his Sept. 20 presentation on the spotted lanternfly.
Spotted lanrterfly pose a threat to fruit trees and vines not only because of the danger they pose to the plant, but also because farmers have reported the fruit from trees attacked by the invasive insect lack the proper amount of sugar, ruining their harvest. The insect poses a threat to Pennsylvania’s $134 million grape, peach and apple industries.
Jim Derr, chairman of the Pottstown Environmental Advisory Commission, examines an exhibit showing the life cycle of the spotted lanternfly during a Sept. 20 presentation at Pottstown Borough Hall.
This slide shows how credit cards can be used to scrape spotted lanterfly egg masses off whatever they are attached to and put into a plastic bag to be destroyed. Each mass contains 30 to 50 eggs.