New Pest on the Horizon

Written by: Maria Panasuk, ISA Certified Arborist #WI-1479A

Posted: 2024 | Emerald Ash Borer | Insect Control | Plant Health Care | Summer

Spotted lanternfly is a type of leafhopper. Although it has wings, it is a weak flier. Unfortunately, this doesn’t make capturing them any easier because of their strong legs. They are incredibly good jumpers, avoiding predators by gliding to other trees. As a nymph, this cute little jumper is primarily black with white spots. As it develops, its back turns red. A mature adult has two sets of wings, the bottom set a bright red, and the top a translucent gray with black spotting. SLF goes through one life cycle per year. The nymphs emerge in late April, becoming full grown by July. In the fall, adults lay a 1.5-inch-long gray egg mass containing between 30-50 insects.

SLF is a type of sap sucker, meaning it has a pierce-sucking mouthpart that taps into soft tree tissue to feed on the sap. The undigested sugar water that the insect excretes is called honeydew. This clear, sticky liquid attracts other insects, primarily bees and wasps. Honeydew can then grow sooty mold, causing leaves to appear blackened.

Although SLF is reported to feed on 50 different plant families, they have a few favored host plants. The top two impacted plants are the tree-of-heaven, an aggressive invader that is on the WI-DNR’s restricted list, and grapes, both wild and cultivated. SLF will feed on these two species throughout the growing season. The adults feed on river birches, willows, sumacs, and red/silver maples. The nymphs that feed from May-July are focused more on roses and black walnuts.

Despite the potential threat of this invasive insect, there is a silver lining to handling SLF.  Depending on the timing and the size of the trees being affected, proper treatments can effectively reduce the impact of this insect.  Wachtel Tree Science can help you and your trees.

Independent populations of SLF have not yet been reported in Wisconsin. However, they are present in neighboring states of Indiana, Illinois, and Iowa. If you see this insect, let your Wachtel Tree Science ISA Certified Arborist know!

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