Blackie Jensen's Blog: The Invasive Spotted Lanternfly: Know What To Do

By Christine Menapace

Landscapers in Pennsylvania, New York, New Jersey, Delaware, Maryland, and Virginia need to be on the lookout for a new invasive insect, the Spotted Lanternfly (SLF), or lycorma delicatula. Feeding on the sap of over 70 types of plants, the planthoppers cause significant damage and even death to ornamentals and nursery plants, as well as forestry and agricultural crops. Many areas where the insect has been found are now under quarantine and landscapers in these areas need to know the rules to avoid fines. Those in bordering areas are urged to help stop the spread of this destructive insect.

Spotted Lanternfly in Chester County, PA

Native to parts of Southeast Asia, the SLF was first identified in the U.S. in Berks County, PA in 2014. Since then, it has spread to 12 other counties in PA, including Monroe, Carbon, Schuykill, Lebanon, Lancaster, Chester, Montgomery, Lehigh, Northampton, Bucks, Philadelphia, and Delaware. In 2017, it was spotted in Frederick County, VA. Last year, three NJ counties, Mercer, Warren, and Hunterdon, were added to the list of quarantined areas. This past September, a single adult insect was found in both Albany and Yates counties of NY.

In areas under quarantine, such as PA and NJ, movement of such things as yard waste, firewood, nursery stock, and other elements of landscaping are restricted. While the insect can only jump or fly short distances, they lay their eggs on any number of surfaces, such as trees, vehicles, and outdoor articles, and thus spread easily from human activity.

So what can you do? First, be able to identify the SLF in all its five stages of growth. (See Illustration.) The first four stages are nymphs, which are incapable of flight. The young nymphs are black with bright white spots and about the size of a pencil eraser. The next stages are similar, but the nymphs become larger. The fourth stage, prior to adulthood, is vibrantly red with distinct patches of black and equally distinct bright white spots. The adult is a leafhopper with 1” long grey wings with black spots that when opened, reveals a bright red underwing. SLFs live through the winter only in egg masses, which can be found from late fall to early spring.

Click to enlarge. (Illustrations by Colleen Witkowski)

Those finding a SLF or a suspicious looking egg mass, should try to destroy it. However, if it is found in an area previously not known, try to kill and preserve it (a container filled with rubbing alcohol or hand sanitizer should work) or at least take a picture and report the sighting to the appropriate state authority. (See contacts at the end.)

Other evidence of SLF are oozing wounds on bark that leave a greyish or black trail. As SLF digests sap, it excretes a substance known as honeydew that, along with sap from these weeping wounds, can attract bees and other insects. There may be a buildup of this sticky fluid on infested plants and on the ground below. The honeydew and sap also provide a medium for growth of fungi, such as sooty mold, which can cover leaf surfaces and stunt growth.

If working in a quarantine zone (which can change as new discoveries are made), know the rules and get a permit where necessary. In PA, a permit provides evidence that you have complete training on the rules of the quarantine order. To obtain a permit, you must take a “train the trainer” free online course, found at https://extension.psu.edu/spotted-lanternfly-permit-training, to teach your employees the compliance procedures.

When traveling in and out of the quarantine zone or even nearby, check your car (including underneath and the wheel well) and any outdoor equipment such as landscaping supplies, mowers, etc. Keep your windows rolled up when you park. Don’t store things or park under infested trees, and don’t move firewood. Also avoid moving woody plant debris (e.g., fallen trees or branches and tree trimmings) and any living plants, equipment, building materials, or other objects.

When working in a quarantined area, if possible chip all woody debris on-site to no larger than 1-inch pieces in each of two dimensions. Ideally, leave all chips or woody debris on-site. The next best option is to take chips or debris to an organic materials recycler within the quarantined area. In PA quarantine zones, if you sell and/or produce mulch you will need to enter into a compliance agreement with the Pennsylvania Department of Agriculture (PDA). (See section below on composting tips to kill SLF.) These regulations do not apply to grass clippings or autumn leaf collection.

Even in areas not yet affected, landscapers may want to recommend clients remove and/or treat any tree-of-heaven (Ailanthus altissima) on their properties, as this is the SLF’s preferred host. Apply herbicide to the tree from July to September and wait at least 30 days before removal. (Failure to apply herbicide will result in new growth from the stump.) In the Spring, band highly infested trees with sticky tape to trap the nymphs crawling up the trees to feed. For both nymphs and adults, insecticides can be used. The most effective ingredients studied include dinotefuran, imidacloprid, carbaryl, and bifenthrin. For a list of products and an IPM guide, see Resources.

Composting To Kill Spotted Lanternfly

To kill viable insects or eggs in chipped material, the following composting procedure can be used:

Compost piles must be a minimum of 200 cubic yards. Internal temperature at a depth of 18 inches must reach 140°F (60°C) for four continuous days.
After the interior is heat treated, rotate the exterior of the pile to the center. Using a front-end loader or a bulldozer, remove the outer layer of the compost pile to a depth of 3’.
Start a second compost pile using the recently removed cover material as a core. Cover this second compost pile by moving the core material from the first compost pile as a cover at least 3’ deep. The second compost pile should remain undisturbed until the temperature reaches 140°F (60°C) for at least four continuous days.