Spotting the Spot - Springtime Spotted Lanternfly Update

As temperatures warm, Spotted Lanternfly (Lycorma delicatula) (SLF) eggs laid last fall will begin to hatch later this spring. The National Phenology Network is forecasting SLF egg hatch in North America based on growing degree day (GDD), base 50F. The map below was captured on Wednesday, April 2, 2025. You can continue to monitor the USA NPN website for SLF egg hatch at: https://usanpn.org/data/maps/forecasts/spotted_lanternfly

While it appears that we are anticipating egg hatch in approximately 2 to 3 weeks in southern Ohio, there is still time to monitor for the presence of egg masses and remove or destroy those egg masses prior to hatch to reduce the population in 2025. 

Last fall, the adult females laid egg masses. Each egg mass typically contains between 30 - 50 eggs. The eggs are laid in rows, or what some describe as chains, and usually are covered as shown below. 

This covering protects the eggs, and although it appears to be smooth and shiny in the fall, the covering does 'weather' over the winter and ages to resemble dried mud, and often will have cracks, as shown in the photo below. 

Egg masses can be laid on any flat surface. While the photos above are laid on trees, the photo below you will noticed the eggs are laid on some wooden building materials. Eggs can also be laid on fences, decorative outdoor art, stone or rocks, vehicles, recreational equipment and more. 

Egg masses can be scrapped off into a container or plastic bag with hand sanitizer or rubbing alcohol, or smashed on the surface they are laid on. PennState University Extension has created a short video to describe both methods. Check out the video online at:  https://extension.psu.edu/how-to-remove-spotted-lanternfly-eggs

Egg masses can also be treated with a soybean oil treatment. Soybean oil, used as an insecticide, is derived from soybean seeds. Insecticide oils can block the air holes through which insects breathe, causing them to die from asphyxiation; act as poisons by interacting with the fatty acids of the insect and interfering with normal metabolism; and disrupt how an insect feeds (Cranshaw and Baxendale 2013). USDA has used Golden Pest Spray Oil™ (GPSO), which is 93% food grade soybean oil. Treatment with the oil will prevent SLF eggs from hatching. Research has shown that it is more effective to treat egg masses just prior to hatch, rather than in the previous fall or early winter. 

So get out there and look - and manage any SLF egg masses now, before they hatch. While SLF is not widespread across Ohio currently, populations continue to spread and are been detected in 18 Ohio counties. The following counties have been under quarantined: Belmont, Columbiana, Cuyahoga, Erie, Franklin, Hamilton, Jefferson, Lorain, Lucas, Mahoning, Muskingum, and Ottawa Counties.  SLF has also been confirmed in: Carroll, Portage, Seneca, Summit, Trumbull, and Wood Counties. Plans are to update the SLF quarantine map in the summer of 2025.  

If you see what you suspect is a SLF egg mass, or SLF egg masses, in a county not listed above, we urge you to report it using the Great Lakes Early Detection Network (GLEDN) App or through the Ohio Department of Agriculture's website using their Ohio Plant and Pest Reporter at: https://survey123.arcgis.com/share/1b36dd2cf09e4be0a79776a6104ce1dc

Another resource you might find helpful is an egg mass comparison sheet created by Virginia Cooperative Extension. I have printed a copy and laminated it for tabling events and other outreach opportunities for people to refer to. You can find this resource at: https://www.pubs.ext.vt.edu/ENTO/ENTO-276/ENTO-276.html

Stay tuned to BYGL for SLF Alerts including first hatch in the week's to come.