Introduction
Spotted lanternfly (SLF), Lycorma delicatula, is an invasive planthopper that was first detected in North America in 2014 in southeastern Pennsylvania. It is native to parts of Asia. SLF is found throughout the state of CT and in many other states. SLF feeds on economically important crops such as grapevines, hops, and several tree species.
Heavy SLF feeding has contributed to the death of grapevines, the invasive tree Ailanthus altissima (tree-of-heaven, or
TOH), and black walnut saplings. SLF feeding can stress plants, cause localized branch damage, and may contribute to the long-term weakening of established plants and trees, it has not been seen to directly kill other plants. In ornamental landscapes, SLF is currently considered to be primarily a nuisance pest. To protect vulnerable plants and industries, it is important to avoid spreading SLF to new areas. Many affected states, including Connecticut, have enacted quarantine orders to prevent or slow accidental human assisted spread of SLF. The
quarantine orders require any items being moved from known infested areas be inspected and SLF destroyed before shipment. The quarantines affect all residents and businesses. Movement of materials from within an SLF restricted area by a nursery or other business should be under permit or compliance agreement. Homeowners and
moving companies should use the checklist available on the CAES SLF webpage.
Complying with the quarantine requires businesses to inspect and take actions to prevent accidental spread. While there are some costs to inspect items being shipped, costs for controlling SLF in plant production
nurseries, vineyards, shipping facilities, and other businesses, could be significant.
Identification and Life Cycle
There is one generation of SLF per year in Connecticut (Figure 1). The eggs are laid in the fall (September to November) and hatch in the spring (late April to June). Egg masses are laid on many surfaces (trees, decks, houses, outdoor equipment, rocks, etc.) and protected with a mud-like covering. Each egg mass contains an average of 35 to 40 individual eggs. After hatching and before reaching adulthood, SLF goes through four nymphal stages called instars. Newly hatched nymphs are small (~1/8 inch) and can be hard to find, often being mistaken for small ticks or spiders. With each molt to the next instar, the nymphs roughly double in size. The first three instars are black with white spots. The last (fourth) instar is red with white dots and black stripes and roughly 1/2 inch long. SLF
nymphs and adults are strong jumpers. In Connecticut, SLF adults begin to emerge in July and remain active as adults until they are killed by the first hard freeze in the late fall.
Adults are the most obvious and easily detectable stage because they are large (about 1 inch) and highly mobile. Adults have black bodies. Their forewings are gray with black spots, and the tips are black with gray veins, while their hindwings are red, black, and white. Only the adults have wings and can fly. However, because SLF adults walk more than fly, their wings often remain closed, leaving only the forewings visible. This makes them more difficult to identify in low numbers, from a distance, or when they are high in a tree.
Current Distribution and Reporting
Spotted lanternfly has been found throughout CT and in many other states. If you suspect you have found a SLF, snap a picture of it and file a report at Connecticut Spotted Lantern Fly (SLF) Reporting (arcgis.com) The reporting portal may be reached by scanning the QR code above. You will be able to include your contact information, and upload photos, but you will not be contacted. All reports are confidential. Businesses should use the SLF checklist (slf checklist.pdf (ct.gov) if moving items out of a regulated area to ensure no insects accompany the move.
Feeding Damage
SLF feeds on plant sap (which is contained in the phloem tissue) using a piercing-sucking mouthpart. They acquire nutrients from the plant sap and also rely on associated bacteria in their guts to support their nutritional requirements. The sap they ingest contains high amounts of carbohydrates (sugar), which is not completely digested by the insect. They excrete the excess as a waste substance called honeydew, which can build up below the feeding insects. On sunny days, honeydew can be seen falling from trees, resembling a light rain. Honeydew is attractive to ants, wasps, bees, and other sugar-loving insects. As the honeydew accumulates, it is often colonized by sooty mold (fungi). Sooty mold does not directly harm plants or the surfaces on which it grows, but it does block photosynthesis in affected plant leaves. With dense groupings of SLF, understory plants may die because of the sooty mold buildup on their leaves. Sooty mold frequently stains objects such as tree trunks, decks, patios, and vehicles that are underneath affected trees. These stains can be very difficult to remove. Consequences of direct feeding damage by nymphs and adults to the host trees vary greatly by host species, numbers of SLF feeding, and environmental conditions. Death of some TOH and branch dieback on other ornamental trees has been reported in cases of high infestation levels.
Some physical damage beneath the bark on branches following heavy feeding has been observed. Based on experiments in Pennsylvania in 2019 and 2020, high levels of adult SLF feeding were found to reduce the photosynthetic activity of some trees. It is possible that after heavy feeding, multiple years of sustained damage, or in particularly dry years, SLF may cause significant damage to ornamental and shade trees.
Seasonal Host Phenology SLF has an extremely broad host range and has been recorded feeding on over 70 different plant species. Conifers are generally not considered to be good hosts for SLF. Despite their broad host range, some plants appear to be more favorable to SLF than others, and host preference has been linked to life stage. Numerous variables appear to determine the attractiveness of a particular plant, the most important being what plants species are available or absent in the nearby landscape. Additional factors include the health of the plant, time of year, the SLF population size, and how long SLF has been present in the area. Nymphs have an especially large host range that includes perennials and any new and tender plant growth, whereas adults seem to depend more on certain hosts, primarily woody stems of trees and mature vines. Not every tree needs to be treated. Researchers have repeatedly observed strong host preference for specific tree species, though the exact trees will be dependent on the surrounding landscape. In 2020, more than 200 trees were assessed for SLF in a 0.1-square-mile shopping center in Pennsylvania. While only 31 percent of the trees were red maples, they held over 94 percent of the SLF population. Scout the area first and then consider treating if high populations are found and persist. Table 1 represents the key plant hosts of SLF and the time at which they are most likely to be found on these hosts; it does not represent a comprehensive list of what SLF feeds on, but rather the patterns of SLF feeding that have been observed through the season. As plants begin to senesce at the end of the growing season, they are less likely to serve as hosts for SLF. The patterns of host use may change with varying weather conditions, by region, or due to yet unknown factors. Please note that while TOH (Ailanthus altissima) is a strongly preferred host, it is not a required host in the development of SLF. However, preliminary evidence suggests that access to TOH may speed SLF development time and improve fitness. Access to multiple host plant species rather than a single host species, regardless of TOH availability, has also been shown to improve fitness.
Article Credit The Connecticut Agricultural Experiment Station