The spotted lanternfly (Lycorma delicatula), an invasive planthopper from Asia, has proliferated rapidly across the Eastern United States since its detection in 2014. This presence often leads to the frustrating experience of having them land directly on people, raising the question of why humans seem to be a preferred landing spot.
Context: Understanding the Spotted Lanternfly
The adult spotted lanternfly is a visually distinctive insect, measuring about one inch long with a half-inch width when at rest. Its forewings are a light gray color patterned with numerous black spots. When startled or in flight, the insect reveals its hindwings, which are a striking scarlet red with black spots and a band of black and white stripes near the edge.
Adults emerge starting in mid-July and remain active until the first killing frost of late autumn. This life stage is responsible for laying the egg masses that overwinter. The species is highly polyphagous, feeding on over 70 different host plants, including grapes, maples, and its preferred host, the invasive Tree-of-Heaven (Ailanthus altissima).
The Science of Attraction: Why They Land on People
The primary reason a spotted lanternfly lands on a person relates not to a specific attraction to humans, but to physical and visual limitations in its biology. As a planthopper, the adult insect is a relatively poor flyer, relying more on a burst of thrust followed by a descending glide. This poor flight control means that when they take off, their trajectory often ends in an indiscriminate landing on the nearest available surface.
The insect’s visual system is strongly predisposed to seeking out tall, vertical silhouettes, which they perceive as suitable launch or feeding structures. They are visually drawn to objects like telephone poles and large tree trunks. A human body moving through an infested area presents a similar, large vertical target, often resulting in an accidental landing.
Movement and vibration also play a role in their sensory environment. Studies indicate that both nymphs and adults exhibit an attraction to low-frequency vibrations, specifically those around 60 Hertz. While this research is primarily focused on developing trap technology, the subtle vibrations generated by a person walking, running, or even standing could draw the insects closer. The combination of visual attraction to a vertical object and physical attraction to subtle ground vibrations increases the likelihood of a close-range encounter.
The physical characteristics of a human may offer supplementary cues. Humans are warm objects, and the lanternfly is visible in the infrared spectrum, though a direct behavioral attraction to this heat (thermotaxis) has not been confirmed. Furthermore, some scientists hypothesize that the carbon dioxide from exhaled breath or moisture from perspiration may resemble plant-based cues.
Safety and Mitigation: What to Do Next
A common concern when an unfamiliar insect lands on you is the risk of a bite or sting, but the spotted lanternfly poses no direct physical threat to people or pets. The insect possesses piercing-sucking mouthparts designed solely for extracting sap from plants. These mouthparts are not capable of penetrating human skin, and they are not known to transmit diseases to humans or animals.
Due to the insect’s status as a highly destructive invasive species, the widely recommended action is to destroy any adult spotted lanternfly you encounter. Immediate action often involves simply stepping on the insect. Since they are planthoppers and tend to jump forward when startled, stepping down directly in front of them is the most effective method for immediate eradication.
Personal Mitigation Strategies
For personal mitigation, reducing the visual and physical cues that attract them can help. Since they are drawn to vertical structures, avoiding standing near known host plants, such as the Tree-of-Heaven, or areas where they are congregating can reduce landings.
Using a small personal fan while sitting outdoors can create air movement that physically disrupts their poor flight path, preventing a close-range approach. When working outdoors in highly infested areas, minimizing the amount of exposed skin and wearing lighter-colored clothing may also make you a less visually prominent target.
Other practical deterrence methods involve managing the nearby environment. Inspect outdoor items like vehicles, furniture, and grills for the gray, putty-like egg masses before moving them to new locations. The destruction of egg masses, which are typically laid on smooth surfaces in the late fall, and the use of tree traps during the nymph stages are the most effective ways to reduce the population in the following year.