The spotted lanternfly (Lycorma delicatula) is an invasive planthopper from Asia that poses a major threat to North American agriculture and forestry. This pest uses piercing-sucking mouthparts to feed on the sap of a wide variety of plants, leading to weakened plant health and, in some cases, death. Since its initial detection in Pennsylvania in 2014, the insect has spread rapidly, impacting numerous states and causing significant economic concern for industries like grapes, fruit, and timber. The insect’s broad diet of over 70 host species means that its feeding habits affect plants across agricultural, commercial, and residential landscapes.
The Primary and Essential Host
The most important tree in the spotted lanternfly’s life cycle is the invasive Tree of Heaven (Ailanthus altissima), which is the preferred host for adult insects. Feeding on this tree significantly improves the insect’s fitness, leading to higher survival rates and greater reproductive success. Nymphs and adults show a strong preference for this species, often clustering in large numbers on its trunks in late summer and early fall.
While the lanternfly can complete its life cycle on other plants, feeding on the Tree of Heaven allows for faster nymphal development and the laying of more eggs. This preference is linked to secondary compounds within the plant sap required for the insect’s reproductive maturation. Removing nearby Tree of Heaven plants is an effective management practice that reduces local populations by eliminating this reproductive hub.
High-Value Agricultural and Commercial Targets
The most significant economic damage occurs in commercial vineyards and orchards. Grapevines (Vitis species) are highly susceptible to damage, with severe feeding leading to vine death and yield reductions as high as 80 to 90 percent in heavily infested areas. Sap feeding depletes the vine’s stored resources, making the plant vulnerable to winter injury and reducing its ability to produce fruit the following season.
Commercial fruit trees are also targeted, including:
- Apple
- Peach
- Cherry
- Plum
While the insects do not feed on the fruit itself, their activity on the trunks and branches stresses the trees. High densities of lanternflies can contaminate crops near harvest and may affect fruit quality by reducing sugar content. Hops, a high-value crop used in brewing, is another agricultural plant the spotted lanternfly frequently feeds upon.
Common Residential and Ornamental Targets
The spotted lanternfly feeds on many residential and ornamental trees beyond commercial hosts. Maple trees (Acer species), including red maple and silver maple, are frequently targeted by adult lanternflies. This feeding stresses the trees, which is a concern for the maple syrup industry where sugar maples are tapped.
Black walnut (Juglans nigra) is a tree of particular concern, as heavy feeding causes shoot dieback, and young saplings can be killed outright. Other common landscape trees that suffer from feeding include willow (Salix spp.), birch (Betula spp.), and sumac. Nymphs often target softer, more succulent hosts in the spring. While the lanternfly stresses these trees, it is not known to be the sole cause of death for established, healthy hardwood trees, unlike its impact on grapevines and young walnut trees.
Recognizing the Signs of Feeding Damage
The signs of feeding are consistent across all host species. One noticeable symptom is the weeping of sap from wounds created by the insects on the trunk and stems. This sap often ferments, producing a distinct, sour or vinegar-like odor around the base of the infested tree.
As the lanternflies feed, they excrete a sugary liquid waste product called honeydew. This sticky substance coats the leaves, branches, and the ground beneath the tree. Honeydew is then colonized by sooty mold, a black fungus that grows on the sugar-rich residue. This layer of black mold inhibits photosynthesis and further weakens the plant. Inspection should also include searching for egg masses, which resemble a smear of gray or yellowish-brown mud found on tree bark or any smooth outdoor surface from fall through spring.