If you are spending time in West Virginia’s northern and eastern panhandles during the summer of 2024 there is a high chance that you will see either nymphs or adult insects of the invasive spotted lanternfly (Lycorma delicatula). The spotted lanternfly continues to spread in West Virginia. The insect was introduced into the United States from China and was first detected in Pennsylvania in 2014. As of February 2024, the spotted lanternfly has been confirmed in 13 of West Virginia’s 55 counties. Although most prolific at present in the northern and eastern panhandles of West Virginia, populations of the insect have also been detected in north central West Virginia as well. The 13 West Virginia counties where spotted lanternfly have been detected thus far are Hancock, Brooke, Ohio, Marshall, Monongalia, Taylor, Mineral, Hardy, Grant, Hampshire, Morgan, Berkeley, and Jefferson.
The spotted lanternfly causes damage to plants by feeding on a plant’s sap. This feeding deprives it of moisture and nutrients. Under heavy feeding, decline and mortality can occur. Many species are believed to be susceptible to damage from the spotted lanternfly, but the preferred host is an invasive tree species known as the tree-of-heaven (Ailanthus altissima). Tree-of-heaven serves as a mechanism to boost populations of spotted lanternfly.
Spotted lanternfly produces copious amounts of honeydew (excrement). This honeydew covers surfaces beneath where they are feeding and a mold called black sooty mold grows on the honeydew. The mold stains all surfaces a black color including any plants that are growing beneath the spotted lanternfly infestation. This mold reduces the photosynthetic activity of plants and can cause reduction in vigor and mortality of understory plants.
Aesthetics are another issue that spotted lanternfly present. They tend to swarm in large numbers in and on buildings. They also tend to land on people when they are outdoors during work and recreational activities. Although the insects don’t bite or cause any harm to humans, most people don’t appreciate attending a sports event with spotted lanternfly crawling all over them.
While complete eradication of this pest is unlikely from most properties, there are control measures that help to greatly reduce their presence and impact. First and foremost is to remove tree-of-heaven. The effectiveness of this measure increases with parcel size (i.e. a small city lot may be devoid of tree-of-heaven, but if surrounding lots contain a lot of tree-of-heaven, then its likely that the spotted lanternfly will spill over into the small, tree-of-heaven free parcel as well).
Simply cutting tree-of-heaven will actually increase its abundance as the roots send up hundreds of sprouts. Herbicides must be used to kill the plant. Herbicides containing the active ingredients triclopyr or glyphosate are quite effective at controlling this invasive plant. Herbicides are generally effective between early summer and late fall. Depending on factors such as tree-of-heaven size, abundance, and presence of non-target species, various application methods are more or less appropriate. Foliar applications during summer are a good choice if there are a plethora of stump and/or root sprouts, but the cut stump method, in which herbicide is quickly applied to freshly cut stumps is best if there are large tree-of-heaven that could become hazard trees if killed and left standing. Landowners should be certain that a tree is truly a tree-of-heaven before removal to prevent the accidental removal of native species such as black walnut that look similar to tree-of-heaven. A guide to assist with tree-of-heaven ID can be found on the WVDA website Spotted Lanternfly: West Virginia Department of Agriculture (wv.gov).
There are both systemic and contact insecticides that effectively control spotted lanternfly. If a landowner/manager has large shade trees, ornamental trees, or even tree-of-heaven that are not feasible to remove, then systemic insecticides can be used. Examples of systemic insecticides effective at controlling spotted lanternfly are products that contain the active ingredients Dinotefuran or imidacloprid. A good contact insecticide for killing spotted lanternfly is any product that contains the active ingredient bifenthrin. As an alternative to insecticides, a solution of 10% dish soap and 90% water may also be used as a contact kill method for spotted lanternfly.
It is important that the applicator read all pesticide labels very carefully before applying to food crops such as grapes. The label will state whether the product is safe to use on food crops. If the label permits use on food crops, the person applying the product should pay close attention to preharvest intervals which state the duration of time that should pass between insecticide application and harvest.
During the winter months, spotted lanternfly egg masses should be smashed. A variety of tools commonly found around the average home can be used to smash the egg masses. Since each egg mass contains 30 to 50 eggs, this is a very efficient and chemical free method to reduce numbers of spotted lanternfly. Egg masses can be destroyed by simply using a sharp flat object such as a putty knife or a plastic bucket opener to scrape/roll over the egg mass in a top-down direction so as not to scrape the eggs off and onto the ground intact.
The spotted lanternfly is an excellent hitchhiker and their spread is significantly enhanced by their ability to hitchhike on vehicles and transported items. Inspection of vehicles and transported items for spotted lanternfly is important, particularly when traveling from or through areas having a confirmed population of the invasive insect.
A common question is why do we care about spotted lanternfly if they prefer tree-of-heaven? It’s not the damage to tree-of-heaven that is an issue, it is the feeding on desirable plants that is of concern. In West Virginia, secondary hosts that are of specific concern are black walnut, wild and cultivated grapes, Virginia creeper, sumac, and several species of maple. There is the possibility that spotted lanternfly feeding could not only stress these species but also spread disease as they move from diseased plants to healthy plants. Given the ability of tree-of-heaven to readily resprout, it would seem unlikely that spotted lanternfly will substantially reduce tree-of-heaven abundance. It would seem more likely that tree-of-heaven will continue to enhance populations of this insect pest and increase feeding pressures on secondary hosts.
Studies and general observations have indicated that the insect cannot be sustained across all life cycles on many of the secondary hosts. In areas with few or no tree-of-heaven, spotted lanternfly is either absent, or significantly reduced in number. Removing tree-of-heaven from timberlands is an important tool in mitigating the impact of spotted lanternfly on West Virginia forests.
