The Spotted Lanternfly (SLF) nymphs are very active in the Delmarva region and moving north as the growing degree days increase in the United States. Host plants include over 70 species of ornamental trees, multiflora roses and bittersweet vines, along with the more commonly associated host, the Tree of Heaven (Ailanthus altissima). There is one generation per year and the eggs laid in the fall are the overwintering stage. SLF can move 3-4 miles per year.
The UMD Landscape and Nursery IPM Report indicates they are about the size of a large aphid currently and move quickly when spotted to the other side of stems. The most reliable way to determine activity in your area is to correlate the transition of the nymphal stages with Growing Degree Days (GDD) through the summer.
The small, black and white spotted nymphs are wingless, so they crawl or jump to feed. As they grow in size to the fourth instar they develop a red pattern that covers most of their body. Size ranges from 1/8” to 5/8” from first to fourth instar respectively. Nymphs prefer tender leaf tissue high in the canopy, as compared to their adult stage, the nymphal stages cannot fly and which can make them harder to see.
Adults emerge by mid-July (GGD 1,100) up until first frost. At rest they are about 1” long and ½” wide, appearing quite different than the mature stage. Their exquisite wings are gray with black spots at the front and speckled bands on the bottom third of the wings. When wings are spread at the base, the hind wings can be seen showing a distinct scarlet color with white spots in the front and white with black bars at the rear. The abdomen is yellow with black stripes.
As phloem feeders, swarms of adults gathering in large numbers to feed on stems can cause the plant to ooze sap. This excretion is known as honeydew and encourages the growth of black sooty mold. This will not kill the plant, but sooty mold can interfere with leaf photosynthesis. Furthermore, if a host plant is heavily infested nearby, it can make living conditions uncomfortable due to the dripping of sap and staining of objects (patio furniture, pavers, etc.) or personal belongings. Excreted fluids also can leave the bark appearing wet and give off fermented odors. Weeping sap can attract wasps as well. Once mating occurs, female adults will fly off and lay eggs on other trees (mentioned below) or man-made objects.
Recommended control measures now include the use of sticky bands that can be placed 4’ from the bottom of trees to trap young nymphs as they emerge from egg cases (i.e., typically May -Oct). There are various resources for sticky bands. The drawback is the sticky surface may potentially capture other small birds and animals. The use of duct tape with the sticky side facing in and coating with petroleum jelly is a homemade option. PDA (Pennsylvania Department of Agriculture) recommends not getting petroleum jelly on bark as it can discolor or injure young, thin barked trees. This method is a useful tool for monitoring and capturing young nymphal and adult stages of the lanternfly.
Chemical Control Options
Penn State Extension has compiled a list of insecticides for landscape and garden use because nymphs can be spread out in landscapes by the last nymphal stages, sprays could be targeted from mid-May through August. Foliar sprays may impact non-target organisms and require repeated sprays. The most effective option in controlling adults are foliar applied chemicals that contain bifenthrin, carbaryl, dinotefuran or imidacloprid. Systemic insecticide drenches (e.g., dinotefuran, imidacloprid) are most effective when applied in spring and early summer before adults build in population. Marathon (imidacloprid) applied after bloom binds to the soil more tightly than Safari (dinotefuran), requiring a longer uptake period to be effective, which when applied July-Sept after plants bloom has very rapid uptake. It is the responsibility of the applicator to check labels and state laws for legal use of recommended products.
Mycoinsecticides are very useful in the nursery trade to control many insects especially when combined with an insect growth regulator (IGR). Azadirachtin is an excellent IGR and is sold under tradenames such as Azatin O, AzaGuard, Aza-Direct and Molt-X.
Removing the Tree of Heaven is a mechanical way of reducing the preferred host tree for this invasive pest. Please contact GGSPro for information regarding timing and use of herbicides to control the Tree of Heaven trees.