Pest ID Tools: Spotted Lanternfly Egg Masses
With the first hard frost of the year behind us, any spotted lanternflies around may have died off, but any eggs they laid will remain, surviving over the winter until they hatch in May. Now is an important time to check for signs of SLF egg masses, since the eggs will be easiest to see on bare trees.. Female spotted lanternflies will lay eggs on nearly any flat surface, which makes them a challenge to survey for, and means there is a big risk of them being accidentally introduced into our state from vehicles or goods that come here from infested states. That makes it critical for as many people as possible to learn to identify these egg masses and distinguish them from any lookalikes.
SLF egg masses have been found on some unusual items, not just trees, as these photos from Pennsylvania show:
Female spotted lanternflies lay one or two egg masses, with 30 to 50 eggs in each mass. The masses are usually covered in a protective coating that looks like a waxy putty, starting out white when fresh and later drying to resemble a gray, cracked, patch of mud. This rough gray surface works well as a camouflage on many surfaces, including tree bark, rocks, and weathered wood. Exposed or uncovered eggs resemble strings of connected seeds.
The easiest things to confuse with SLF egg masses would be the egg masses of the spongy moth (Lymantria dispar). Spongy moth egg masses can be found from late August until May on almost any vertical surface. They can be distinguished from SLF egg masses by their buff or yellowish fuzzy coating, and also often have tiny pinprick holes on the surface, evidence of parasitic wasp activity. The eggs themselves, which can be seen by scraping away the fuzzy covering, are small and spherical, compared to the larger and more oval eggs of lanternflies.
You may also come across mud wasp or mud dauber nests on the sides of structures or under roof overhangs. Mud daubers are solitary wasps and are a native insect that create cylinders of mud to house their eggs. The shape and large size set them apart from SLF egg masses.
We also sometimes get reports from people who confuse SLF egg masses with lichens. Lichens are a hybrid of algae and fungus and found in many habitats. They have a wide variety of appearances but commonly have a scaly-looking appearance and some of the most common ones are flat and have a bluish-green tinge. These are harmless, naturally-occurring growths and can be left alone. However, SLF egg masses could be camouflaged amongst a lichen-covered surface, so you should always check to make!
If you think you have found a spotted lanternfly egg mass, please photograph what you see and report it here. If you are not able to take a photograph, you can use one of our plastic ID cards (order some for free here) or a credit card to scrape the eggs off, place them in a bag or other sealable container, and add rubbing alcohol as soon as you can – this will kill the eggs.