Where are the spotted lanternflies in Central PA? Canadian wildfires might have an impact

Where are all the spotted lanternflies this year?

The invasive bugs have infested south-central Pennsylvania in recent years, but so far this summer, they haven't been seen in high numbers.

Spotted lantern flies have been detected in counties known to have them, but they seem to be delayed this year, said Jay Losiewicz, deputy communications director with the state Department of Agriculture.

The insects are still in their instar phases and have not grown into their most visible stage as an adult, he said in an email.

"Their life stages are temperature and daylight dependent, so it's possible the smoke from the Canadian wildfires may have an impact," Losiewicz said. "Research is ongoing, but we don't yet know why the delay is occurring."

Insects, including spotted lanternflies, have swings in population sizes

Spotted lanternflies were first discovered in Berks County, Pennsylvania in 2014. They have spread to other counties in the state, including Adams, Lebanon and York.

It's mostly the northern tier of the state that seems to have been spared from the invasive species.

Spotted lanternflies often reach high populations, especially when they first come into a new area, said Emelie Swackhamer, horticulture extension educator with Penn State Extension in Montgomery County. As the years go on, the populations fluctuate.

"Some years we have more and some years we have less, and we don't really understand all the reasons why that happens," she said.

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Tree of heaven, other host plants attract spotted lanternflies

A couple of different factors have an effect on the spotted lanternflies' ability to build high populations, Swackhamer said. One involves the availability of host plants and their health.

Spotted lanternflies love the tree of heaven, an invasive species from Asia. If residents have the tree on or around their property, they will likely see the bugs every year, she said.

The species does have some natural enemies. Spiders, wheel bugs, praying mantis and some birds will catch and eat them. How many predators are in the area could affect the population, she said.

Some fungi will attack the bugs, too. That happened in Berks County in 2018. The fungi killed many of the adult spotted lanternflies before they could lay eggs in the fall, which resulted in fewer of the insects the following spring.

People also take control measures by treating an area before the spotted lanternflies can lay eggs.

"We don't have a way to predict future populations based on any measurement of these factors," Swackhamer said. "We would love to have a way to do that, but we, at the moment, can't do that. We need more research."

While it's possible to have a year of low numbers in certain locations, it's usually localized, she said.

Just wait. The spotted lanternflies could still show up.

The eggs of spotted lanternflies hatch mostly in May. So if people are not seeing the nymphs in their area, it might indicate a lower population this year, Swackhamer said.

When they turn into adults and start to move around more, that could change, she said, especially if property owners have plants on their land that the bugs are attracted to in the fall.

Grape growers, for example, will be keeping a watchful eye on their vineyards. The bugs like to feed on the sap of the grapevine, which stresses the plant, Swackhamer said.

Spotted lanternflies also will go to red and silver maple trees and some birch trees in the fall.

"And just because you don't see many of them right now, keep watching," she said. "You should be diligent."

What should I do if I find spotted lanternflies on my property?

If people find the spotted lanternflies on their property, they should think through the risk and make an educated decision about whether they need to take any action. Penn State Extension has a management guide to help people mitigate the pest, Losiewicz and Swackhamer said.

If homeowners only see a few bugs or they are on an undesirable plant, such as the tree of heaven, the risk is low, Swackhamer said.

But if a whole lot of them are on a favorite ornamental plant or grapevine, the risk would be greater and the owner might want to take action.

Different management options exist, and people are encouraged to start with the least toxic options, Swackhamer said.

Property owners might want to remove the tree of heaven to reduce the numbers.

They also can build or buy circle traps to capture them. It's best to set them out in May when the eggs are hatching, she said.

If people decide they need to use a treatment, insecticidal soaps, botanical oils and pyrethrums can work.

Experts do not recommend using home remedies because they are not tested for safety on the plants. It could do more damage than the bugs. In addition, the concoctions are not safe for people, Swackhamer said.

As a last resort, homeowners could hire a professional licensed pesticide applicator to get rid of them, she said.

Sticky bands are not recommended because other wildlife can get trapped in them and die. People who use them should build a guard to help prevent harming other creatures.

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How to avoid spreading the spotted lanternflies

The state Department of Agriculture has a quarantine for the counties where the spotted lanternflies exist.

Everyone is required to avoid spreading the spotted lanternfly, Swackhamer said.

Businesses and organizations must have a permit to "move vehicles, equipment and goods within and out of the zone," according to the PennState Extension website.

They must take a free online course offered by Penn State Extension and the state Department of Agriculture and pass quizzes to be granted permits. It is available on the Penn State Extension website, extension.psu.edu/spotted-lanternfly.

While residents are not required to have a permit, they are encouraged to check their vehicles and things they are moving to avoid spreading the pest.

"We need everybody's help," she said.

This article originally appeared on York Daily Record: Spotted lanternflies: Canadian wildfires, population swings explained