Spotted Lanternflies Are Here

It’s that time of year again. It’s springtime, and the trees will soon be blooming, crocuses popping up in the garden, and spotted lanternflies emerging from a long winter nuzzled in their protective egg cases. 

The latter is not a good thing. Spotted lanternflies are an invasive species and cause serious damage to crops, vines, trees and other types of plants. The colorful insect is native to China, Vietnam and Bangladesh and was first discovered in Pennsylvania in 2014 in Berks County.

Now the species has spread to 34 counties, mostly in the southeastern portion of the state. That is eight more Pennsylvania counties than in 2020. 

Early stage nymphs feeding

We asked Academy Animal Programs Developer Karen Verderame what we can expect to see this spring regarding the pesky plant hopper and what we can do about it. 

What’s happening now in the southeastern Pennsylvania and southern New Jersey region?  

Lanternflies are estimated to start emerging towards the end of March, once temperatures start to steadily warm, triggering them out of their dormant state. 

What happened with the egg masses over the winter? 

Spotted lanternflies, like many other insect species, overwinter in their egg cases. This is called diapause, and it’s a delay in growth and development that allows some insects to be dormant in cold winters. In fall 2020 when temperatures started to cool down in the Pa.-N.J. region, the adult lanternflies started laying egg masses to allow the nymphs to survive the winter. Now that it’s spring, and temperatures are starting to warm, this triggers the nymphs to come out of their dormant state and continue developing and eventually hatch. How cold the winter was and how prolonged the warmup will be are factors in determining exactly when we’ll start seeing the first instars of lanternflies hatch.

Late stage nymph

Do you think the public’s efforts over the fall and winter to scrape away the egg masses will result in fewer spotted lanternflies hatching this spring? 

This first-ever public campaign to kill the egg masses will certainly help reduce some numbers. However, there can be many egg masses in hard-to-reach places such as off of highways, high up on trees and on trains traveling through. It will be interesting to see how populations of lanternflies will differ as they have settled into some regions vs. areas where they have just started to be seen.  

Did the unusually large snowfall and cold temperatures in our area affect them?  

Lanternflies experience diapause, a slowing of growth and development, to overwinter in their eggs. Though we saw higher snowfalls than usual in our region, our temperatures were not that significantly lower than usual. The first instars may be a little late emerging, but most likely most egg masses survived the winter. In 2020, we had a “warmer” winter, therefore in some areas we saw an earlier emergence of first instars at the beginning of March, rather than later March.

Adult spotted lanternfly

Why will we see both black and white nymphs and black, white and red nymphs? 

These are different instars of the nymphal stages of spotted lanternflies. Lanternflies will be black with white spots from their first through third instars. They will be red with black and white spots in the fourth instar before turning into winged adults. It is common to see various stages throughout April-June because the many various egg masses will be developing and hatching at different rates. Location can play a factor. If an egg mass was laid in a sunnier spot, it will warm quicker, triggering the end of their dormant state.  

Do either of the two nymph stages harm people? Harm crops? Harm trees and plants? 

No stages of the spotted lanternfly are harmful to humans. They can be harmful to crops, plants and trees as all stages of the lanternfly feed on various species of plants and trees. Their excrement is dewlike that can cause a mold which can kill trees, particularly when you have masses of them feeding on the same tree. Nymphs typically feed on new growth on plants and trees.  

What should we do if we see the nymphs? 

If you see nymphs it is best to try to destroy them.  

How can we get rid of them? 

It is difficult to be rid of them, but it is important to try to combat them as best you can. There are a variety of ways to try to destroy the nymph stage, but each common method comes with its own challenges. Stomping on them has the least amount of impact on native wildlife and plants. It can be challenging to stomp the nymphs as they are good jumpers. There is also tree banding, where you wrap trees with a sticky tape to catch nymphs as they crawl up. However, this can be detrimental to native insects and other wildlife. There are modifications that can be done to tree bands to help try to make it safer for beneficial insects and wildlife.  

What happens after they outgrow their nymph stage and how will the warm weather affect them? 

Typically around July is when we see the fully winged adult stage of the spotted lanternfly. Like many insects, spotted lanternflies are exothermic, which means they depend on outside sources to regulate their body temperature. Being exothermic, warmer weather makes them more active. That is why we more commonly see them flying more and on the move in late summer.  

What can we expect this summer?! 

I think we can expect to see a widening of range for the spotted lanternfly as at the end of last season there were reports of sightings further into New Jersey, Delaware and New York.  

How do we get rid of the flying spotted lanternflies? 

Now that word is out on the spotted lanternfly, communities can work together in combating them when they see them in their area to help prevent further spread. Penn State Extension has many resources on how to combat the spotted lanternfly.  

Does climate change have any effect on them? 

Climate change could affect how often and when we see spotted lanternflies. Their growth and mating are triggered by environmental temperature cues.  If our area sees warmer seasons, we could see prolonged seasons for spotted lanternflies.  

By Karen Verderame and Carolyn Belardo. Images courtesy of Penn State Extension.

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