July 12, 2024
Spotted lanternfly (SLF; Lycorma delicatula) continues to pose a threat to the environment, economy, and society in Canada. These insects have had detrimental effects in parts of the U.S., including neighbouring states such as Michigan, New York, and Ohio. With the warmer weather increasing outdoor recreation and travel over the U.S. border in the next few months, vigilance will be key for spotting any SLF nymphs and adults that could potentially make their way into Canada this summer, along with egg masses, which can be present as early as late September.
SLF are planthopper insects believed to have been introduced into the U.S. between 2012 and 2014. Adults have pinkish-grey forewings approximately 1” long with black spots and black veins at the tips. The underwings are bright red and are visible when the forewings are open. The abdomen is yellow with black stripes. Nymphs in 1st to 3rd stage of development (instar) are black with white spots, and 4th instar nymphs are red with black spots. Nymphs are visible from April to July, adults from July to October, and masses from as early as late September until April.
Although the preferred host for SLF is the invasive tree-of-heaven, they also feed on numerous other plant species including cultivated grapevines, fruit trees, and black walnut. Their fondness for a variety of plant species enables them to potentially establish across a wide geographic range, and they are able to thrive in urban and suburban areas. SLF’s feeding practices can weaken and sometimes kill plants, especially grapevines. The insects excrete a sweet, sticky substance called honeydew that builds up at the base of the plant and surrounding ground. This can lead to the growth of sooty mould, which can reduce the photosynthetic capacity of the plant.
Along with causing significant damage to plants, SLF can also have other impacts. The honeydew attracts other insects that can potentially sting, like bees, hornets, and wasps. It can even rain down from a swarm of SLF in tree canopies onto people walking underneath, reducing the enjoyment of the outdoors during the summer.
SLF has already had negative economic impacts on U.S. agriculture, including heavy losses incurred by grape growers. In a 2019 study, researchers found that damages caused by SLF to Pennsylvania agriculture amounted to $42.6 million annually statewide (Harper et al., 2019). If the insects establish themselves in Ontario, it could have significant impacts on agriculture, especially Ontario’s grape and wine industry.
Although there continues to be a risk of SLF establishment in Ontario, to date there have been no detections, only sightings and interceptions as defined by Canadian Food Inspection Agency (CFIA). These definitions, along with observations occurring in Canada are publicly accessible and can be found here: Spotted lanternfly observations in Canada – inspection.canada.ca. If you think you’ve found SLF, remember to take a photo, catch the insect and place it in a sealed bag or container, and report it right away to CFIA.
The Invasive Species Centre, along with partner organizations is providing training to partners and members of the public this summer to increase surveillance and ensure early detection of SLF in Ontario. A free self-paced, online SLF training course is available on the ISC website. To learn more about SLF, visit www.invasivespeciescentre.ca/spottedlanternfly.
