Be on the Lookout for Spotted Lanternfly!
By Robert Bruner
Spotted lanternfly (SLF) has been the subject of a lot of media attention in the last few years. States like Pennsylvania and New York have been dealing with heavy infestations since the insect was first detected in 2014. In Indiana, this invasive planthopper arrived three years ago, infesting Switzerland and Huntington counties on the eastern side of the state. Since then, SLF has spread across several northernmost counties in the state, and it’s been spotted as far south as Bartholomew County. This unique insect is originally a native of Asia, existing in small populations in association with their host plant, the tree-of-heaven (Ailanthus altissima). The Indiana Department of Natural Resources and Purdue University have been working together to mitigate the spread of this insect, as well as educate Hoosiers on how they can help. Spotted lanternfly is still on the move, and keeping up-to-date on this bug’s ecology and life cycle is critical to protecting your business, properties, and the natural areas you love.
Life cycle
Eggs
Spotted lanternflies lay eggs in masses of between 30 to 60 eggs arranged in rows. The female covers the eggs in a protective substance that closely resembles mud, making detection of egg masses challenging to the unexperienced eye (Fig. 1). Sometimes, the covering is only partially or lightly applied, so observers may see neat, parallel rows of small, oval-shaped eggs stuck to a surface. Eggs are laid in the late summer/early fall and overwinter until the new generation hatches in early spring, starting the cycle anew. 
Fig. 1
Nymphs
Spotted lanternfly is an annual insect, typically having only a single generation in a year. The insect develops through incomplete metamorphosis; immature stages, called nymphs, resemble smaller, wingless versions of the adults. Nymphs will emerge in April to May, developing through four instars, or periods between shedding their exoskeleton. With each instar, the nymphs grow larger, develop wingpads, and change color. Early instar nymphs are black with a white dot pattern, while later instar nymphs will be bright red with black and white patterning (Fig. 2). Late-instar nymphs are easily confused for a number of insect look-a-likes, such as milkweed bugs or lady beetles (Fig. 3). It should also be noted that SLF nymphs have a protrusion from their head that make them easy to confuse for insects such as weevils or a curculio, but this protrusion is lost once they become an adult.
Adult
Adult SLF are small, flighted insects whose body and wing shape resemble their distant cousins, the cicadas. They are approximately one inch in length and a half inch in width, with wings that form a roof-like shape over the abdomen. The forewings are beige with a pattern of black dots and black wing tips. The hindwings are a striking bright red, with black and white stripes (Fig. 4). The abdomen is bright yellow with black stripes, though that may one be seen when wings are spread or if the abdomen is distended.
Once they reach adulthood in the late summer or early fall, SLF will seek potential mates and food resources. After mating, female SLF will lay egg masses on a multitude of surfaces, including their host plant, vehicles, train cars, boats, even under the eaves of a house. Adult insects will die as temperatures cool in the Fall. In Indiana, depending on temperature, adults are seen as late as November.
Fig. 2
Impact
Spotted lanternfly has piercing/sucking mouthparts, also known as a rostrum. These mouthparts act just like a syringe that the insect inserts into plant tissues, draining out nutrient-rich sap from the host plant. This insect feeds from the trunk or stem of a plant and typically leaves behind dark streaks of sap. SLF feeds in large groups on individual plants, making detection of live insects relatively easy. As SLF feeds, they take in large amounts of sugar that their bodies are unable to process, so they excrete it as sugary waste known as ‘honeydew’. Honeydew drips down from infested plants, covering understory foliage and creating a substrate that allows the growth of sooty mold. While sooty mold doesn’t damage a plant directly, it severely limits its ability to photosynthesize. Additionally, feeding activity creates wounds that open the host plant up to potential infection by pathogens, though there is no evidence of a pathogen directly associated with SLF as of the writing of this publication.
Fig. 3When attacked by SLF, most plants will survive the damage and continue to grow. However, SLF often returns to the same trees each year in large numbers. The consistent re-infestation will take its toll, reducing the tree’s overall resilience and ability to overwinter. Plants such as black walnut, maple, American river birch, and grapes are particularly susceptible to feeding damage from SLF. Grapes are especially sensitive to infestation, suffering reduced yield and possible death from overfeeding.
As mentioned above, the invasive tree-of-heaven acts as the primary host plant for spotted lanternfly. Tree-of-heaven has been present in North America since its introduction in the 18th century. Tree-of-heaven is a major nuisance; it will choke out native greenery, damage buildings and sidewalks, and overtake a landscape if there are no mitigation efforts in place. The relationship between spotted lanternfly and tree-of-heaven has held firm in new environments. In Indiana, established infestations are associated with tree-of-heaven, though they will infest other plants, such as maple and black walnut, when tree-of-heaven become overpopulated. However, there is not yet any evidence that the presence of spotted lanternfly will provide any control of tree-of-heaven.
Fig. 4
Where are they now?
As of Jan 2025, SLF has been detected in Huntington, Switzerland, Elkhart, Allen, Grant, Boone, Miami, Noble, Dekalb, Bartholomew, Porter, St. Joseph, Wabash, and Ohio counties. This insect has been progressively moving through the state, and often the locations where it’s found are associated with railroad tracks with unmitigated stands of tree-0f-heaven. Researchers and professionals working to contain this insect are also beginning to find small populations of SLF on secondary host plants, such as maple, near areas with heavy infestations. This could mean that SLF is beginning to fill space on their primary host and move to other plants in an effort to food, mates, and oviposition sites; however, more research needs to be done to confirm this.
What can I do?
As of the writing of this article, the Indiana Department of Natural Resources is still managing efforts to eradicating infestations of SLF, along with the removal of tree-of-heaven. However, given the speed at which this insect is moving, individual businesses and property owners will soon need to take action to control its spread. In the near future, check for information on treating SLF from sources such as Purdue Extension, the Indiana DNR, and similar organizations. We are still learning about the spotted lanternfly’s distribution through Indiana, and we need the help of citizen scientists to track the insect’s movement effectively. If you believe you’ve seen spotted lanternfly, please report it using any of the resources listed below. You can also reach out to Bob Bruner, Exotic Forest Pest Educator, by emailing them at rfbruner@purdue.edu, or you can report sightings by calling 1-866-NOEXOTIC. Keep an eye out, and have a great time at state fair!
Special thanks to Dr. Alicia Kelley for her help in reviewing this publication!
Robert Bruner is an Exotic Forest Pest Educator with the Department of Entomology at Purdue University. Bob’s work focuses primarily on invasive insects, such as spotted lanternfly and spongy moth, but he does a significant amount of work on other invertebrates or invasive pathogens.
Resources:
Indiana Department of Natural Resources Reporting Tool:
https://www.in.gov/dnr/entomology/pests-of-concern/spotted-lanternfly/
Early Detection and Distribution Mapping Systems:
Great Lakes Early Detection Network: