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Monitoring an Invasive Species: Spotted Lanternfly

July 19, 2023

By Abbie McHardy, Student Entomologist, Royal Botanical Gardens

Be on the lookout for the spotted lanternfly (Lycorma delicatula), or ‘SLF’! This insect is native to Asia but currently inhabits areas of the United States. It was first documented in the US in 2014 and has established populations in several areas throughout the country, as it’s moving further and further North (Urban & Leach, 2023).

It is predicted that it’s only a matter of time until the SLF migrates to Southern Canadian provinces such as Ontario. The most common method by which the SLF migrates is by laying egg masses on shipping cargo, transport trucks, or other vehicles which then move into different areas before the eggs hatch (Urban & Leach, 2023). This insect will not only pose a major threat to many areas of the agricultural industry namely vineyards and wine production, but it will also threaten many plant communities in the province and country. It is highly invasive and extremely versatile in its’ feeding habits, having the ability to feed on a very wide variety of plants (Urban & Leach, 2023). There are very few known predators to SLF in the US, most of which include birds and fishes (Urban & Leach, 2023). There are also very few methods devised to help manage and mitigate population growth of these insects.

SLF As a Nuisance Pest in Urban Settings

In its’ adult phase, the SLF is a conspicuous insect that can be unattractive and a major nuisance pest in urban landscapes. They have been documented covering tree trunks as they feed from the phloem of these woody plants, and thousands of adults can inhabit a single tree trunk (Urban & Leach, 2023). The droppings that they produce are a viscous, sticky liquid called honeydew, which covers the ground as well as any low understory plants located beneath their colonies. Accumulations of honeydew can grow mould and mildew, suppress the growth of small understory plants, as well as attract Hymenopterans such as ants and stinging wasps (Urban & Leach, 2023).

Life Cycle and Identification

The spotted lanternfly, Lycorma delicatula, is a phloem-feeding planthopper (family Fulgoridae). This insect overwinters in egg mass form, which in Pennsylvania are laid in early fall (Urban & Leach, 2023). Egg masses are fairly nondescript, so it is important to become familiarized with them so that you are able to identify them, report them, and remove them before they hatch. If you have travelled through Pennsylvania or other Northeastern US states, it is important to inspect your car for these egg masses once you arrive home. As seen in Figure 1, SLF egg masses are light gray in colour, and appear hard and crusty in texture (Ministry of Agriculture, Food and Rural Affairs, 2023). To properly remove them, first take a clear photograph, then scrape them off the substrate using a credit card or a knife, into a container of vinegar or alcohol to ensure that they are killed (Ministry of Agriculture, Food and Rural Affairs, 2023).

Spotted lanternfly egg mass on a tree trunk
Figure 1: Spotted lanternfly egg mass on a tree trunk

When eggs hatch in early summer, nymphs will emerge in their first instar, which is shown in Figure 2. These are tiny and all black in colour, with little white spots covering their backs and legs. First-to-third instar nymphs are similar in appearance, with the only difference being a slight increase in size through the later instars. In the fourth instar, however, nymphs will be more recognizable as they are bright red in colour, with black borders, black legs, and a black stripe down the middle of their back, extending from the thorax to almost the tip of the abdomen. They also have white spots on their backs, as well as tiny wing buds, or developing wing structures (Ministry of Agriculture, Food and Rural Affairs, 2023). In Southern Ontario, we are currently experiencing weather that is optimal for SLF to be entering its fourth instar, which is the most conspicuous of the nymphal instars. It is important to keep your eyes open for a small red, black, and white insect, with an elongated head and small wing buds (Figure 3).

First to third instar nymph of spotted lanternfly
Figure 2: Appearance of the first-to-third instar nymph of spotted lanternfly
Fourth instar nymph of spotted lanternfly
Figure 3: Fourth instar nymph of spotted lanternfly

After the fourth instar, the spotted lanternfly will molt one final time to become a fully developed adult. In Pennsylvania, adults appear in late summer and are prevalent until the onset of winter (Urban & Leach, 2023). Adults are quite large, and have two sets of wings, the first of which are pale red or tan in colour with black spots. The wing tips are covered in densely placed black flecks. The second set of wings are bright red with black spots at the wing base, and a black wing tip with a white stripe. When their wings are folded, they appear tent shaped, with only the forewings visible. The spotted lanternfly completes one generation per year (Urban & Leach, 2023).

Adult spotted lanternfly with its’ wings open perched on the side of a tree
Figure 4a: Adult spotted lanternfly with its’ wings open
Adult spotted lanternfly with wings closed perched on moss
Figure 4b: Adult spotted lanternfly with wings closed

Host Plants

While spotted lanternfly feeds voraciously on almost any plant in its early instar nymph phases, it specializes slightly in the fourth instar as well as the adult phase, as it prefers to feed through woody tissues of certain plants. The main host trees that SLF will target in these two life stages include; tree of heaven (Ailanthus altissima), various grape trees (Vitus spp.), black walnut (Juglans nigra), red and silver maple (Acer rubrum and Acer saccharinum), and willow trees (Salix spp.) (Urban & Leach, 2023).

Reporting a Sighting of SLF

If you spot SLF in any of its’ life stages, it is important to report it to the Canadian Food Inspection Agency (CFIA). To do so, take a clear photograph, and include the location and date found, as well as the host plant or other item or material on which it was found (Ministry of Agriculture, Food and Rural Affairs, 2023). A sample specimen may also be submitted, however, ensure that the specimen is dead before transporting it. This can be done by placing it in alcohol or vinegar (Ministry of Agriculture, Food and Rural Affairs, 2023).


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