Over the past few months, invasive spotted lanternflies have emerged in massive numbers across Maryland.
Originating in Asia, the spotted lanternfly is an invasive pest that feeds on a variety of plants. The lanternfly was first detected in the United States in Berks County, Pennsylvania, in 2014. It is suspected that the species was accidentally carried into the United States through an international shipment of stone.
Although the insect first appeared in the United States over a decade ago, it has only been seen in Maryland since 2018. Since then, the species has spread throughout 20 out of 23 counties in the state, according to the Maryland Department of Agriculture.
What harm do they pose?
Spotted lanternflies are not directly dangerous to humans. Although their flitting around can be irritating, the insects do not sting or bite. There also has not been evidence of spotted lanternflies being poisonous to eat or being dangerous to pets.
However, because they feed on plant sap, spotted lanternflies pose a threat to the well-being of a number of plant species in Maryland. Grapes are particularly at risk of harm: their feeding risks killing off grapevines. They also enjoy feeding on maple and willow trees.
When feeding, lanternflies excrete honeydew, a substance which is known to grow fungus. This “sooty mold” fungus will not directly kill a plant, but in large quantities, may stifle photosynthesis by blocking its access to sunlight. The fungal growth may also prevent crops from being sold.
“They’re seeing damage, almost permanent damage, to things underneath of the trees,” Jessica Boyles, the coordinator for the Maryland Department of Agriculture’s spotted lanternfly response program, told Capital News Service.
Boyles mentioned that she has heard reports of damage to landscaping, siding, and outdoor equipment such as grills and furniture due to honeydew and sooty mold.
Excess honeydew may also pose another threat: attracting unpopular stinging insects, such as wasps, hornets and honeybees.
Why are they everywhere?
Spotted lanternflies are notorious for hitchhiking to new places on cars and trains. Because each female typically lays between 30 and 50 eggs, lanternfly populations can explode in just a few years. These egg masses can be hard to spot, closely resembling mud splotches.
Without native natural predators, lanternfly populations can develop under the radar over several years until they emerge in unignorable numbers.
“It really wasn’t all of the sudden,” Dr. Michael Raupp, a professor of entomology at the University of Maryland, said.
“They were really here for several years, but at low levels,” Raupp stated. “Now, because they’ve had time for their populations to increase, we’re seeing them everywhere.”
What can I do?
Contrary to popular belief, some experts say that killing an individual spotted lanternfly does little to curb the insect’s population growth.
“The thing that regulates their population are predators, parasites and diseases,” Raupp said. “So, by stepping on some spotted lanternflies, it’s kind of like spitting in the ocean and thinking you’ve turned back the tide.”
Instead, Maryland’s Department of Agriculture recommends installing circle traps, which capture spotted lanternflies without using chemicals that may put other insect populations at risk.
These traps wrap around trees to funnel spotted lanternflies into a dead-end container, and can be either purchased or made at home. It may also be helpful to dispose of egg masses if you see them.
Spotted lanternflies prefer to feast on the Tree of Heaven plant, which is another invasive species from Asia. Removing a Tree of Heaven (roots and all) from your yard can help avoid attracting the insect.
Lastly, checking your vehicles before traveling can also help to prevent the spread.
“Make sure that you don’t bring spotted lanternfly with you on your daily commute,” Boyles said.
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Ultimately, however, experts forecast that spotted lanternfly populations will eventually subside once they begin to face more predation and disease.
“Eventually, Mother Nature will take care of this, as she does with many of our invasive species,” Raupp said.
Some areas have already begun to see population declines due to an increase in predators and disease.
“We now have more than 1,000 observations of indigenous vertebrates and invertebrates eating spotted lanternflies,” Raupp said.
Some of these predators include spiders, mantises, chickens and pheasants.
This is not to say, however, that stomping lanternflies is futile.
“If you’re killing one…you are making sure that that spotted lanternfly can’t essentially quadruple its numbers,” Boyles said.
As lanternflies continue to lay eggs up until the first frost, often in December, it can still be worth it to squash the pests, experts say.
Why bother reporting?
Currently, the state’s Department of Agriculture is still accepting reports of spotted lanternfly sightings across Maryland. Although officials acknowledge that total eradication of the species is unlikely, reporting helps the agency to allocate resources to areas experiencing large populations of lanternflies.
“That information is vital,” Boyles said. “It does help us.”