The Spotted Lanternfly (SLF) is an invasive planthopper that originated in Asia (China, Taiwan, and Vietnam) and was first found in the United States in Pennsylvania in 2014. This insect poses a threat to North American ecosystems and economies, leading state and federal agencies to urge the public to eliminate it on sight. The rapid spread of this pest, largely facilitated by human activity, endangers billions of dollars in agricultural and timber industries across multiple states through direct crop damage, secondary problems from its waste product, and regulatory burdens.
Threat to Agriculture and Vineyards
The Spotted Lanternfly has a devastating impact on high-value specialty crops. The insect feeds by using piercing-sucking mouthparts to draw large volumes of sap from the host plant’s phloem tissue. This feeding depletes the plant’s stored starches and reserves, weakening its overall health and ability to survive harsh conditions.
Grapevines are particularly vulnerable; heavy adult infestations sometimes result in up to a 90% reduction in yield and rapid vine decline. Feeding near harvest time disrupts the plant’s ability to accumulate carbohydrates for overwintering and affects the sugar content needed for ripening. SLF also targets other commercially grown fruit, including apple, peach, and cherry trees, as well as hops plants. The collective damage to the viticulture, fruit, and nursery industries can translate into hundreds of millions of dollars in annual losses.
The Problem of Honeydew and Sooty Mold
Beyond direct feeding damage, the Spotted Lanternfly causes secondary harm through its waste. As the insect consumes large quantities of plant sap, it excretes a sugary liquid called honeydew. This sticky substance coats the leaves, stems, and surrounding surfaces beneath the feeding insects.
The honeydew acts as an ideal growth medium for a black fungus known as sooty mold. When this mold blankets the leaves, it inhibits photosynthesis. This reduction in the plant’s ability to create energy stresses the host, leading to reduced growth, lower fruit yields, and increased susceptibility to diseases. The honeydew and resulting mold also create a nuisance in urban and suburban areas, coating outdoor furniture, decks, and vehicles, and attracting pests like wasps and ants.
Economic Impact of Quarantines
The presence of the Spotted Lanternfly forces state and federal agencies to establish quarantine zones to prevent its spread, creating economic challenges. These regulatory zones strictly prohibit the movement of the insect in any life stage and regulate the transport of “regulated articles” that could harbor the pest. Regulated items include nursery stock, firewood, construction materials, and outdoor household goods like grills and lawnmowers.
Businesses operating within or moving goods out of quarantine areas must comply with measures such as obtaining permits and implementing self-inspection checklists. Commercial entities, especially those in trucking, logging, and landscaping, must train employees and undergo inspections to ensure their vehicles and cargo are free of the insect. This regulatory compliance disrupts interstate commerce and supply chains, increasing operational costs for businesses, which are often passed on to consumers. Studies in Pennsylvania estimated that, if uncontrolled, the pest could cause hundreds of millions of dollars in annual economic losses and thousands of lost jobs due to crop damage and containment costs.
How the Public Should Respond
The public plays a substantial role in slowing the spread and reducing the population of the Spotted Lanternfly. Individuals should kill the adult insect on sight by squishing, stomping, or crushing it. Eliminating adults prevents them from laying the next generation of eggs.
Individuals should search for and destroy egg masses, which look like a smear of gray or brownish-gray mud on smooth surfaces. Egg masses, which contain 30 to 50 eggs, should be scraped off the surface—using an old credit card or putty knife—and destroyed by placing them into a sealed plastic bag containing hand sanitizer or rubbing alcohol. Reporting sightings outside of established infestation zones to local or state agricultural departments is important for monitoring and containment efforts.