The Spotted Lanternfly (SLF) is an invasive planthopper that poses a serious threat to agriculture and native plants. This pest, native to Asia, feeds on the sap of over 70 plant species, causing significant stress and damage to crops like grapes, hops, and various hardwood trees. While the adults are noticeable, the most effective way to limit the spread and population is by finding and destroying the egg masses. These masses represent the only stationary stage in the life cycle, making them the primary target for mitigation efforts. A diligent search for these masses during the dormant season is the single most impactful action a resident can take to help control the species.
When and Where to Search for Egg Masses
The optimal time for citizens to search for and scrape egg masses is from late fall through early spring. Adult female SLFs begin laying eggs in the fall, typically starting in September, and continue until the first hard freeze. The egg masses then overwinter, surviving the cold until they hatch into nymphs starting in May and June.
The search must be thorough because the female is non-selective about where she deposits her eggs. While masses are often found on the trunks of trees, especially the invasive Tree of Heaven (Ailanthus altissima), they appear on almost any outdoor surface. Common locations include stone walls, patio furniture, grills, firewood, and metal objects.
The pest often lays eggs in protected or hidden areas, such as the undersides of picnic tables, tree limbs, or in the wheel wells and undercarriages of vehicles. Since the egg masses are commonly laid on items that move—like RVs, shipping containers, and vehicles—checking everything before transport is highly important to prevent the pest from spreading. These masses are typically laid ten feet or lower on trees, but checking higher and in unusual spots remains important for a complete search.
Identifying the Key Visual Characteristics
A newly laid Spotted Lanternfly egg mass has a distinct appearance that changes as it ages and weathers. The female first lays 30 to 50 eggs per mass in vertical rows, then secretes a protective covering over them. This fresh coating is initially a creamy white or gray-white and has a thick, waxy, putty-like texture.
As the covering dries and is exposed to the elements, it hardens and darkens, often turning a light grayish-brown or tan. At this stage, the mass is frequently mistaken for a splotch of dried mud, cement, or clay, which provides natural camouflage. The entire mass is small, usually measuring about one to one-and-a-half inches long and three-quarters of an inch wide.
The protective covering will eventually degrade, becoming cracked, flaky, and lighter in color. This wear exposes the individual eggs underneath, which look like rows of seeds. Once the nymphs have successfully hatched, the mass will appear completely empty, leaving behind only the remnants of the vertical rows with small oval openings.
Look-Alikes and Proper Removal Technique
Identifying the egg mass can be complicated because the pest’s camouflage resembles several common outdoor objects. A frequent point of confusion is differentiating the SLF mass from the egg cases of beneficial insects, such as the Praying Mantis. Mantis egg cases, called oothecae, are typically frothy, lighter in color, and much larger. They often contain distinctive, elongated cells that are not present in the SLF mass.
Other items that can be confused with the mass include patches of lichen, dried mud splotches, or the fibrous egg masses of other moths. The unique combination of the size, the smooth or cracked putty-like texture, and the presence of the seed-like eggs in vertical columns distinguishes the SLF mass from these look-alikes.
Proper Removal Technique
When an egg mass is confirmed, the removal technique must be precise to ensure destruction. The process requires a stiff, flat object, such as a plastic card, putty knife, or paint scraper. The mass should be scraped off the surface with firm, deliberate pressure, ensuring that every egg is crushed or removed. Simply scraping the mass onto the ground is not recommended, as the eggs may still survive and hatch. The scraped material must be immediately destroyed by placing it into a sealed plastic bag containing hand sanitizer or rubbing alcohol. The alcohol or sanitizer ensures that the eggs are killed, after which the sealed bag can be disposed of in the trash.