The Spotted Lanternfly, Lycorma delicatula, is an invasive planthopper from Asia that poses a significant threat to agriculture and forestry across the United States. Since its detection in Pennsylvania in 2014, this pest has spread rapidly due to its wide host range and propensity for hitchhiking. The insect utilizes piercing-sucking mouthparts to extract sap from the phloem of over 70 different plant species, weakening the host and causing substantial economic damage.
The Critical Role of Tree of Heaven
The single most important host plant for the Spotted Lanternfly is the invasive Tree of Heaven, Ailanthus altissima. While the lanternfly can survive on many plants, its overall biological fitness is maximized when it feeds on this specific tree. Studies show that adult females feeding on Ailanthus produce a significantly higher number of eggs compared to those feeding on other species.
When lanternflies are deprived of this preferred food source, their development is slowed, and their reproductive output is substantially reduced. The tree’s unique chemical composition contributes to the lanternfly’s defenses, as those feeding elsewhere lose chemicals that make them unpalatable to predators. Strategic removal of Ailanthus altissima trees has become an integral part of area-wide management plans for the pest.
Secondary Food Sources
Beyond its primary host, the Spotted Lanternfly feeds on a wide variety of secondary plants that are often of high economic value. Nymphs and adults feed on the sap of cultivated plants, including grapevines, hops, and various fruit trees like apple, peach, and cherry. They also feed on numerous shade and timber species, such as maples, willows, birches, and black walnut trees.
The insects’ habit of congregating in large numbers to feed can significantly stress plants, leading to reduced yield in crops like grapes, and causing dieback in young trees. For instance, heavy feeding on grapevines can deplete the plant’s carbohydrate reserves, dramatically increasing the risk of vine death during the winter.
Attracted to Sugars and Fermentation
The primary chemical attraction for the Spotted Lanternfly is the high sugar content found in plant sap, which they access using their specialized mouthparts. As they feed, the insects ingest large volumes of this sugary liquid to extract necessary protein and nitrogen. They excrete the excess sugar and water as a sticky liquid called honeydew, which can rain down from heavily infested trees.
This honeydew is a powerful attractant for other sugar-loving insects, including ants, wasps, and bees. Furthermore, the feeding wounds created by the lanternflies cause the host plant to weep sap, which quickly begins to ferment. This fermentation produces alcohols and volatile compounds that act as chemical cues, drawing late-season adults to the damaged areas in search of a final, energy-rich meal before egg-laying.
Visual and Behavioral Attractions
Apart from food-related cues, the Spotted Lanternfly is highly attracted by specific visual and behavioral signals, particularly in the late summer and fall. Adults are visually drawn to tall, dark, vertical surfaces, such as utility poles, the trunks of large trees, and the walls of buildings. This behavior is linked to their dispersal strategy, where they crawl to the highest point to launch themselves into the wind to find new feeding or mating locations.
The lanternflies exhibit strong aggregation behavior, mediated by chemical signals, or conspecific cues. These cues draw both males and females to a shared location for mating and eventual egg-laying. This congregating instinct is why they are often found swarming in large clusters on a single tree trunk or structure, maximizing their chances for successful reproduction.