The spotted lanternfly, Lycorma delicatula, is an invasive planthopper first detected in North America in 2014. This insect, native to Asia, is not a true fly but a member of the order Hemiptera, possessing piercing-sucking mouthparts that allow it to feed on plant sap. Its rapid spread and generalist feeding habits position it as a pest with the potential to cause hundreds of millions of dollars in losses to agriculture and forestry. The multifaceted nature of the damage it causes explains why this species is considered detrimental to the environment and human interests.
Direct Economic Impact on High-Value Crops
The most immediate concern involves the spotted lanternfly’s devastating effect on commercially important crops, particularly vineyards. The insect feeds by inserting its mouthparts into the phloem tissue to extract sugary sap. This intense feeding weakens vines, leading to reduced winter hardiness, poor fruit set, and, in severe cases, the complete death of the grapevine. Some vineyards in heavily infested regions have reported yield reductions of 80% to 90% in a single season.
Adult lanternflies often aggregate in large numbers on grapevines, with reports of up to 400 individuals found on a single vine. This feeding pressure occurs late in the season, directly disrupting the vine’s ability to accumulate the reserves needed to survive the winter and produce fruit the following year. Beyond grapes, the spotted lanternfly feeds on other high-value crops, including stone fruits, apples, and hops. This forces growers to implement costly and frequent insecticide treatments.
The Pervasive Problem of Sooty Mold
The damage caused by the insect extends beyond direct feeding due to a sticky, sugary waste product it excretes, known as “honeydew.” The lanternfly consumes vast quantities of sap, expelling the excess sugar water in large volumes. This honeydew coats the leaves, branches, and trunks of plants, as well as surfaces beneath the infested trees, including decks, furniture, and vehicles.
The sugary residue acts as a growth medium for a specific type of fungus called black sooty mold. As the mold grows, it forms a dark, thick layer that obstructs sunlight and inhibits photosynthesis. This reduction in light absorption further weakens the plant, contributing to its decline. The honeydew and sooty mold also create a significant public nuisance by attracting other insects like wasps and bees.
Biological and Behavioral Drivers of Spread
The spotted lanternfly’s success as an invasive species is driven by its biological characteristics. It is an extremely polyphagous insect, meaning it can feed on over 70 different host species, including maples, walnuts, and willow. This broad diet allows the pest to thrive in diverse environments, from forests to agricultural fields, even without its preferred host, the invasive Tree-of-Heaven (Ailanthus altissima).
In its native range in Asia, the lanternfly’s populations are naturally regulated by specific parasitic wasps and other enemies that are largely absent in North America. While native North American predators have been observed consuming the insect, they have not been sufficient to keep the population in check.
Humans play a major role in the insect’s rapid spread across state lines through a behavior known as “hitchhiking.” Females lay their egg masses, which contain 30 to 50 eggs, on nearly any flat, outdoor surface, including cars, shipping containers, and outdoor equipment. The egg masses are covered with a protective, mud-like substance that camouflages them, allowing them to be unknowingly transported long distances.