Spotted Lanternfly (SLF) is an invasive insect species native to parts of Asia, including China, Vietnam, and Bangladesh. First spotted in the U.S. in Pennsylvania in 2014, efforts to contain this insect pest have been aggressive, but it has spread throughout the state and has now been seen in surrounding states.
The good news is that Spotted Lanternfly does not bite people. The bad news is, lanternfly decimates many food crops and landscape plants, including grapes, peaches, roses, blueberries, apples, maple, birch, cherry, sycamore, willow, staghorn sumac, cucumbers, basil, daylily, and others (at last report, there were 65 known species of plants). Spotted Lanternfly does not feed on the fruit of food crops – they feed on the woody parts of the trees and plants, which affects the long-term health of the plant. SLF is most likely to be found in their host plants: Tree Of Heaven (Ailanthus altissima), also an invasive species, black walnut, and hops.
How does Spotted Lanternfly kill plants?
Spotted Lanternfly has piercing, sucking mouthparts and is a big planthopper. This pest uses its mouthparts sort of like a straw – they insert it into the sap conducting vessels (the phloem) of a plant and feed on the sap. When the SLF is young, the mouthparts are tender and they tend to feed on the undersides of leaves and the petioles of leaves – the tender parts of a plant. As they mature, the mouthparts become stronger, and the insects can pierce through old bark on trees and feed on the sap.
Like many other insects, SLF leaves “honeydew” in its wake – sap from the tree that is relatively undigested, which has passed through their body. There are lots of sugars remaining in the honeydew, which attract fungi, putting further stress on the tree. Honeydew appears as a sticky, black, sooty mold with a sour smell and may settle on the fruit, which ruins it.
To make matters worse, stinging insects thrive on honeydew – it’s not unusual to see a yellow jacket literally following an adult Lanternfly and sucking up the honeydew as it emerges from the Spotted Lanternfly’s body.
SLF is not known to do any structural damage to homes. Even though they may collect en masse on a wall, they won’t try to get inside the wall space and overwinter as other insects do. The adults will die during the winter from cold temperatures.
What are the natural enemies of Spotted Lanternfly?
Currently, the only known natural enemies of SLF are Praying Mantids, spiders, and wheel bug (an assassin bug)
Which organic insecticides kill Spotted Lanternfly?
Researchers are still experimenting with insecticides to combat Spotted Lanternfly. As of this time, these 4 insecticides approved for organic growing show an effect on SLF. Note that they will treat insects present on the plant at the time of application but will not kill visitors after application (they are not systemic). The 4 organic insecticides are:
- Insecticidal soaps
- Natural pyrethrins (synthetic pyrethrins are not approved for organic)
- Neem oil
- Spinosad
Learn how to build a circle trap to catch and kill Spotted Lanterflies.
The life cycle of Spotted Lanternfly
Female SLFs lay eggs in September in egg masses. Each female can lay up to 2 egg masses with each mass between 30-50 eggs. The female lays her eggs in rows and covers them with a secretion from her body which is at first white but dries to a mud-like appearance. The covered egg masses are easy to miss as they are laid in protected areas where they will stay warm over winter. They’re also easy to miss on trees as they blend in with tree bark or be mistaken for actual mud. SLF egg masses can be found anywhere, including objects you would never suspect the insect would use. Spotted Lanternfly is frequently moved this way – objects with egg masses are moved to other geographies, their owners unaware of the insects.
SLF has only one generation per year. Young Nymphs emerge from the eggs in spring and has 4 nymphal stages, each of which is called an instar (every time a nymph sheds its skin it’s the next instar). In the first 3 instar stages, SLF are black with white spots. In the 4th instar, they develop a red coloration (see images below).
Spotted Lanternfly goes directly from 4th instar to adult without the aid of a cocoon or pupa. The skin of the last instar cracks open and the adult crawls out. At first, the adult is light in color but darkens as it quickly dries. It can easily be identified by its black spots on its folded wings.
You can find more resources on Spotted Lanternfly from the Pennsylvania Department of Agriculture and Penn State University.
Images: Penn State Extension.