The Spotted Lanternfly (Lycorma delicatula) is an invasive insect first detected in Pennsylvania in 2014. Native to parts of Asia, it has spread rapidly across the United States, causing concern due to its destructive feeding habits on plants. This article addresses whether this pest poses a direct physical threat to people or pets and explains the true nature of the environmental risk it presents.
Do Lanternflies Pose a Threat to People?
The Spotted Lanternfly does not bite, sting, or attack humans or domestic animals. Their anatomy is not designed for defense or predation against large animals, and they are not known to carry diseases transmissible to people. They lack the necessary mouthparts for biting through human skin and do not possess a stinger.
While they are not dangerous to human health, large infestations can become a significant nuisance. Swarms of these insects often congregate on outdoor structures, making outdoor activities uncomfortable. There is no scientific evidence that they are venomous or cause allergic reactions, though some people may experience symptoms from the mold that grows in their waste.
Pets that ingest a Spotted Lanternfly may experience temporary symptoms like an upset stomach or drooling. This reaction is usually mild and is often attributed to the insect not being a part of a regular diet. Scientists are researching whether lanternflies sequester toxic compounds from their preferred host plant, the Tree of Heaven, which could make them unpalatable to wildlife.
Understanding the Lanternfly Feeding Process
The Spotted Lanternfly belongs to the order Hemiptera. Their mouthparts are designed specifically for piercing plant tissue, not for biting or chewing. This specialized feeding structure is a long, needle-like apparatus known as a proboscis or rostrum.
The proboscis allows the insect to drill into the plant’s vascular system, specifically the phloem, to access the sugary sap. As obligate sap feeders, they rely entirely on this plant fluid for nutrition throughout all life stages. Since the sap inside the plant is under pressure, the fluid is delivered directly into the insect’s mouthparts when the tissue is pierced, requiring minimal effort.
The strength of the proboscis varies by life stage. Nymphs feed on softer, current-year growth, while adults can penetrate the woody tissue of trunks and older growth. This feeding behavior dictates the wide range of host plants the insect targets, which includes over 70 species of trees, vines, and shrubs.
Environmental Impact of Lanternfly Feeding
The primary concern surrounding the Spotted Lanternfly is the severe damage it inflicts on agriculture and ecosystems. The insect feeds voraciously on a wide variety of plants, including economically significant crops like grapevines, hops, and fruit trees, as well as hardwood trees such as maple and walnut. This massive removal of sap causes stress, branch dieback, and oozing wounds on the host plants.
The continuous feeding can significantly inhibit photosynthesis and reduce the growth of young trees. Studies show a reduction in diameter growth by over 50% in silver maple saplings under high feeding pressure. While the insects rarely kill mature, healthy trees outright, the feeding weakens the plant and increases its susceptibility to other diseases and environmental stressors. The most devastating damage is often seen in vineyards, where high lanternfly densities can significantly reduce yields and sometimes kill the grapevines.
As they consume large amounts of sap, Spotted Lanternflies excrete the excess sugar water as a sticky liquid called “honeydew.” This honeydew creates a cascade of problems, coating the leaves, branches, and surrounding surfaces, including decks and vehicles. The sugary substance promotes the growth of black sooty mold, a fungus that covers the plant’s leaves and blocks sunlight, inhibiting photosynthesis. The honeydew also attracts other insects, such as wasps and bees, which feed on the sweet residue.