Read Spotted Lanternfly: The Need to Remain Vigilant (part 1) here.

The spotted lanternfly (SLF) is an invasive insect pest first detected in Pennsylvania in 2014, with confirmed sightings and/or infestations of SLF now reported in 20 eastern states. SLF is not currently found in California; however, accidental introductions threaten future establishment. From 2022 to the present, there have been 48 interceptions of SLF entering California, with 38 of these found on aircraft during airport inspections. Spotted lanternfly eggs have been intercepted on firewood, metal plates for construction, military equipment, and incoming nursery shipments. While the art structure is one of the most concerning detections to date, spotted lanternfly's behavior of laying eggs on non-plant items contributes to their wide dispersal ability and the likelihood of unintentional introduction into new areas. The identification and early detection of exotic pests are key to preventing their establishment in California. Everyone can play an important role in keeping exotic pests out of California by being the eyes and ears needed for early detection.

The spotted lanternfly (Fig. 1) is a sizable planthopper (about 1 inch long and about 0.5 inch wide) that originates from southeastern Asia. This planthopper has a wide host range consisting of 103+ plant species, with 56 feeding hosts identified so far in North America. SLF has caused economic damage to grapevines along with feeding on fruit trees (apple, cherry, fig, stone fruits), walnuts, blueberries, hops, oak, maple, birch, sycamore, ash, beech, hickory, poplar, willows, and woody ornamentals. Its preferred hosts are the invasive Tree-of-Heaven (Ailanthus altissma), grapevines, maple, and black walnut. SLF have piercing-sucking mouthparts and produce large quantities of honeydew that act as a substrate for the growth of sooty molds. In addition to being an invasive agricultural pest, SLF may also be a nuisance pest in urban areas due to their aggregation behavior.

Figure 1. Spotted lanternflies on grapevines. Photo Credit: Heather Leach, Penn State University.

In Pennsylvania, the spotted lanternfly has one generation per year. Nymphs emerge starting in May and go through four immature stages. Adults start to emerge by late July. SLF overwinter as eggs, which are laid from September to November on smooth tree surfaces and inanimate objects such as telephone poles, stones, pallets, outdoor equipment, firewood, railway cars, vehicles, etc. Each female produces one to two egg masses of 30 to 50 eggs each. Seed-like eggs are laid in multiple successive rows and covered with a yellowish-brown waxy deposit (Fig. 2).  

The first three immature stages are black with white spots and lack wings. The fourth immature stage is red and black with white spots and possess small wing pads. Adults have a stout yellow abdomen with incomplete black bands and two sets of wings: the forewings and the hindwings. The forewings are a tannish-cream color with black spots changing to small black rectangles toward the tips. (Fig 3.) The hindwings are primarily black and red, with black spots appearing in the red portions. The hindwings are not noticeable when at rest.

Figure 2. A) Spotted lanternfly eggs covered with waxy deposit. B) Seed-like eggs with holes where spotted lanternfly nymphs have emerged. Credit: A) Pennsylvania Department of Agriculture, Bugwood.org (left) and B) Kenneth R. Law, USDA APHIS PPQ, Bugwood.org (right). Licensed under a Creative Commons 3.0 License.

The arrival and establishment of SLF in California would negatively impact a range of high value commodity crops by increasing production costs, lowering plant health and productivity, and the impacts of sooty mold on marketability would be devastating. The establishment of SLF could also impact the ability for growers to sell commodities, such as table grapes, for export, potentially resulting in a notable impact on international trade. Research is being conducted to identify effective IPM strategies, including biological control agents, that could be rapidly implemented if SLF were to be discovered in California.

If you suspect you have found SLF, it is important to document and report your sighting to your local county Agricultural Commissioner's office or the CDFA report a Pest Hotline right away. Visit https://www.cdfa.ca.gov/plant/reportapest/ for more information. Nymphs cannot fly and adults do not readily fly away when approached so both can be easily collected. Early detection is key for preventing the establishment of this species. Californians need to remain vigilant and together, we can all play a role in keeping the spotted lanternfly out of California.

Figure 3. 1st thru 4th instar nymphs and adult spotted lanternfly compared to a US quarter. Credit: USDA-ARS Photo by Andrew Dechaine.

Adapted from the UC Master Gardener Program Statewide Blog. Adapted from an article by Cindy Kron, Ph.D published in CAPCA's magazine, "The Advisor" published August 2024.