Spotted Lantern Fly: An Invasive Pest Threatening Trees, Fruit Crops, and Vegetables

Posted on October 31st, 2019

Top view of spotted lanternfly, Chester County, Pennsylvania

The insect Lycorma delicatula, commonly known as the spotted lantern fly (SLF), is an invasive sap-feeding planthopper from Asia, which was detected in the United States in 2014 in Berks County, PA and since has rapidly spread to NJ, DE, NY and VA.  The insect does not bite or sting, but it threatens agricultural commodities including tree fruit (apples, plums, cherries, peaches, nectarines, apricots), almonds, grapes, hops, and a variety of common trees.

The SLF overwinters as egg masses and has a one-year life cycle.  The first nymphs hatch in late April to early May, wingless and incapable of flight. Adults appear in mid-July, with their wings formed, mating in late summer to early fall and form large congregations.  Females lay eggs from late September through October. Egg masses, containing 30-50 eggs at a time, have a gray, mud-like covering, which can become dry and cracked over time.  They are typically found on smooth surfaces on host plants or dead plants, as well as vehicles, trash barrels, and other man-made structures. SLF has even been known to lay eggs on propane tanks or other outdoor equipment with flat surfaces.

The insects feed on different plants, changing host as they go through developmental stages.  Nymphs feed on a wide variety of plants, adults prefer to feed and lay eggs on their favorite host tree (ailanthus altissima, a.k.a tree-of-heaven), which is an introduced invasive species that grows throughout much of the U.S.  As the insect feeds on the plant’s sap, photosynthesis is reduced, the plant eventually dies, and the SLF will relocate elsewhere. The SLF excretes a sticky, sugary substance (honeydew), which attracts other insects (ants, bees, wasps, hornets and flies) and causes the growth of sooty mold on the host plant, surrounding soil and understory plants.

While the insect can independently travel short distances, its long-distance spread is facilitated by human transport of materials housing egg masses.  Quarantines have been issued in many states to slow or stop the spread of this pest, requiring an inspection of any items moved within and out of quarantine areas. States are issuing permits to commercial businesses that transport commodities within and out of quarantine areas. All residents and businesses must comply with regulations, and states have the authority to fine anyone who willfully violates the quarantine order.

Fluctuations in SLF populations have been observed from year to year and may be influenced by natural predators and parasites and/or availability of quality food, however, the fluctuations are not well understood. There are reports of predaceous insects feeding on the SLF; however, these insects are likely not affecting the overall population growth of the SLF. Residents in the infested areas use a variety of methods to control the SLF, including scraping/destroying egg masses, banding trees, trapping, elimination of their favorite host tree or using chemical control/insecticides.

In addition to these methods, the United States Department of Agriculture (USDA) recommends businesses familiarize themselves with SLF quarantine zones, and diligently check vehicles and transported items when moving between zones. As the consulting industry is highly mobile and often involves transport of SLF threatened goods (lumber, tanks, outdoor equipment), it is vital that our industry remain proactive about stopping the spread of the SLF. This destructive invasive pest is a community concern and it is important for everyone to remain vigilant,  using safe, recommended practices to avoid the spread of this species into new areas.  The battle must be won against this destructive pest because its spread can seriously harm the country’s viticulture, orchard, ornamentals and logging/timber industries.



Andrew Thomas, LSRP

Senior Manager

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