I Spotted a Spotted Lantern Fly: What Now?

Richard Gardner, Bugwood.org

As the warmer weather is coming to a close for the year, so is the life cycle for all the spotted lanternflies you may have seen flying around. These insects are unable to survive the colder weather and will die at the first killing freeze. However, the eggs they lay before this will persist and overwinter the species until they hatch the following spring. Egg laying occurs from September to November, varying based on the timing of the killing freeze. The eggs will be present where they were laid until the following June when the first stage of nymphs will hatch from them. A female spotted lanternfly will usually lay two egg masses, with an average of 30-50 eggs per mass.

Locating Egg Masses

Egg masses will usually be laid in close proximity or right on the feeding locations of the adult spotted lanternflies. Plant species they have a preference towards should be the first place to look, such as tree of heaven, red maple, silver maple, and willow. However, a majority of eggs will be laid where they cannot be reached, such as the upper canopy of tall trees; 80 to 90 percent of all egg masses will be laid 10 feet or higher in trees. For the sake of safety, it is not recommended to use ladders to try and reach these. Instead, alternative trap-based methods should be used when the spotted lanternflies hatch the following year. Egg masses will be present on a variety of surfaces though and not only limited to trees. Spotted lanternflies will lay eggs on any hard surfaces, including plastic, metal, or wood, anywhere they occur outside. They can be laid on the underside of the surfaces, so a thorough inspection must be completed.

Identifying Egg Masses

This array from Penn State shows how egg masses present. Photos by Heather Leach.

Egg masses are 1 to 1 ½  inches long,  and ¾  inches wide, arranged in segmented columns. The egg masses might be uncovered, where they are a yellowish to brown color, each about the size of a sharpened pencil tip. They can also be covered by a white putty-like substance that slowly becomes more pinkish gray, and eventually to a scaly darker tan appearance as it dries. Covered egg masses can appear like patches of mud and could be difficult to see at times depending on the surface they were laid on. This cover helps protect the eggs over the colder months, although uncovered eggs will still hatch the following year, just at a lower rate. Female spotted lanternflies prefer to lay their eggs next to already laid egg masses so if you find one, there is a good chance there are more nearby.

 Destroying Egg Masses

 Once located, the simplest method for dealing with the eggs is to smash them. Just be sure to apply adequate and even force to smash the entirety of the egg mass, making sure the eggs burst open as a result. The eggs can also be scraped off the surface, using a hard, tapered, or flat tool such as a plastic card. They should be scraped into a plastic bag containing rubbing alcohol or hand sanitizer to ensure destruction. Eggs that are scraped to the ground can still hatch, so this step is critical. Some egg masses will be impossible to reach, such as those high in the canopy of a tree. Even still, dealing with the eggs that are accessible can help lower the future population in the spring.

William Carter is an Educator at the Bartlett Arboretum & Gardens.