Spotted lanternfly on Plants

Symptoms

Look for branch flagging, wilting, and weeping wounds on tree trunks and branches. These signs come from insects feeding on the phloem tissue of host plants. Heavy feeding by nymphs can cause dieback of individual tree branches.

Large numbers of feeding nymphs can also damage perennials and annuals. A black sooty mold can coat the leaves. That coating reduces photosynthesis and can lead to early leaf drop and dieback. Early leaf drop is one result of the mold, and dieback is another.

On fruit crops, especially in vineyards, you may see a reduced harvest, lower sugar content, and mold building up on the fruit. The stress from this feeding can lead to decreased health and potentially death. Plants can die back when the feeding is heavy. Both nymphs and adults feed on the plant, and either stage can cause this damage. The signs fall into a few groups: wounds and wilting on wood, mold on leaves, and losses on fruit crops.

Causes

Three causes are on record for this problem. The first is feeding by nymphs and adults on the phloem tissue of host plants. The second is long-distance spread when egg masses are transported on vehicles, pallets, and other goods. The third is a life cycle of one generation per year that overwinters as egg masses hatching in spring.

Feeding is what produces the wounds, wilting, and dieback described above. In the egg mass stage the insect moves easily over long distances, which gives it a significant risk of introduction. Both nymphs and adults feed on the phloem, and each stage is part of the cause.

Tree of heaven is an especially favored host, and the pest reproduces there in great numbers. Other listed hosts include walnut, maple, grape, willow, and several fruit crops. With one generation per year, the insects overwinter as egg masses before they hatch in spring.

Diagnosis

Begin with the plant itself. Tree of heaven and crops such as grape, hops, and cherry are among the listed hosts. Perennials and annuals can show damage too when many nymphs feed on them.

Next, look at where the damage is. Weeping wounds and flagging appear on tree trunks and branches, and sooty mold appears as a black coating on leaves. Fruit crops add their own signs: reduced harvest, lower sugar content, and mold on the fruit, especially in vineyards.

Wilting is only one of the signs listed, and it appears alongside flagging and weeping wounds. Dieback of individual branches, early leaf drop, and general plant stress are also on the list of signs. It is large numbers of feeding nymphs that cause the branch dieback.

Egg masses are laid on tree trunks and other surfaces, and they can be scraped off. The cause on record is feeding by nymphs and adults on host plants. The facts on file name no look-alike problems, so this page cannot rule any out for you.

Treatments

Cultural methods come first in the order of treatment. If possible and practical, remove tree of heaven, the preferred host plant. Removing it targets the host on which the pest reproduces in great numbers.

Scrape egg masses off tree trunks and other surfaces into an alcohol solution to destroy them. Scraping works at the egg stage, before the eggs hatch in spring. You can also set a funnel-style circle trap around tree trunks to capture nymphs and adults.

For an organic option, apply less-toxic, registered insecticides such as soaps and oils. Some of these carry an organic label. Soaps and oils are the examples given of these registered products.

The chemical options are listed by type: two named systemic active ingredients and one contact insecticide. Dinotefuran is a systemic insecticide applied as a soil drench, trunk spray, or trunk injection. Apply it after bloom to protect pollinators. Imidacloprid is a soil-drench systemic insecticide, and its low solubility means it requires more time for uptake.

A contact insecticide persists longer in the environment and can kill spotted lanternflies that move into the area even after the spray has dried. This page gives no dose, rate, dilution, or spray interval. The product label is the legal instruction and must be followed for the crop and site being treated.

Prevention

Prevention here comes down to conditions around your plants. The pest reproduces in great numbers on tree of heaven, an especially favored host. Removing it, where possible and practical, takes away the preferred host plant.

Egg masses are easy to move over long distances, and they travel on vehicles, pallets, and other goods. That route is how the insect reaches a new area, since the egg mass stage carries a significant risk of introduction. Egg masses are laid on tree trunks and other surfaces, and scraping them off destroys them.

One generation a year overwinters as egg masses, which hatch in spring. Funnel-style circle traps around tree trunks capture nymphs and adults. Maple, walnut, willow, grape, apple, and cherry are also listed hosts.

Plants most often affected

Spotted lanternfly feeds on tree of heaven, walnut, maple, grape, willow, apple, apricot, cherry, hops, peach, and plum. Tree of heaven is especially favored, and the pest reproduces there in great numbers. Seven of these are crop hosts: apple, apricot, cherry, grape, hops, peach, and plum. Nymphs and adults both feed on these plants.

• American Basswood
• Autumn Olive
• Eastern Poison Ivy
• Norway Maple
• Sassafras
• Sugar Maple
• Tree of Heaven