The Spotted Lanternfly (SLF), Lycorma delicatula, is an invasive planthopper that poses a serious threat to agriculture and forested ecosystems across the United States. This pest feeds by piercing plants and sucking out sap, weakening host species and causing significant stress. The nymph stage involves four distinct growth phases, or instars, and represents a highly mobile and active feeding period. Targeting these nymphs is a proactive strategy to reduce the population before they become reproductive adults.
Identifying and Locating Nymphs
Successful control begins with accurately identifying the nymphs and knowing where they congregate to feed. The first three nymphal instars appear from late spring through early summer. They are small, wingless, and distinctly black with bright white spots, measuring about one-quarter of an inch long.
The fourth and final nymphal stage emerges around mid-summer, becoming noticeably larger—up to three-quarters of an inch—and developing a striking red coloration mixed with the black and white spots. All nymphs possess piercing-sucking mouthparts that allow them to feed on the tender, new growth of over 70 different plant species.
While nymphs have a broad host range, they are commonly found feeding on herbaceous plants, grapevines, and the invasive Tree of Heaven (Ailanthus altissima). Early instars typically feed lower on plants, but the fourth instar nymphs prefer the Tree of Heaven, often climbing higher on the trunks. Their habit of crawling up trunks is a behavior utilized in certain trapping methods.
Physical Removal and Non-Toxic Trapping
Immediate, hands-on removal is an effective, non-chemical method for eliminating nymphs within easy reach. The simplest technique is physical crushing, where the nymphs can be stomped underfoot or smashed with an object. Nymphs are strong jumpers, often launching themselves away when approached, so quick movement is necessary to prevent their escape.
For larger clusters or nymphs feeding on delicate garden plants, a wet/dry shop vacuum or a hand-held vacuum can suction them directly off the plant surface. Once collected, the contents must be emptied into soapy water or placed in a freezer overnight to ensure the insects are killed. Another direct method involves using a strong, pressurized stream of water from a garden hose to knock the nymphs off plants, after which they can be crushed.
Trapping methods capitalize on the nymphs’ habit of crawling up trunks to feed. Circle traps are a non-adhesive option, utilizing a screen funnel to direct climbing nymphs into a sealed collection container. This design reduces the risk of unintended capture of non-target species like beneficial insects or small wildlife.
Sticky bands, which wrap around the trunk to ensnare climbing nymphs, are another common trapping tool. These bands must be protected by a fine mesh or vinyl window screening barrier secured around the sticky surface. Without this shield, sticky bands pose a threat to birds, bats, and other small animals that can become fatally entangled. Any sticky band used should be checked daily, and if a non-target animal is caught, the exposed sticky material must be covered with paper and the entire band removed for safe transport to a wildlife rehabilitator.
Low-Impact Topical Treatments
When physical removal is impractical for large numbers of nymphs, low-impact topical sprays offer a readily accessible method of control. These treatments function as contact killers, meaning the spray must physically touch the nymph to be effective. Application should be highly targeted, focusing only on the areas where the nymphs are actively feeding or clustering.
Insecticidal soaps work by dissolving or disrupting the nymph’s protective outer layer, the cuticle, leading to dehydration and death. These soaps require thorough coverage to be effective and are useful for spot-spraying clusters of nymphs. Horticultural oils, often derived from petroleum or plant sources, kill the nymphs by coating and suffocating them.
When using horticultural oils, avoid application during hot, sunny conditions, as this can increase the risk of phytotoxicity, which is damage to the plant foliage. Neem oil provides a three-pronged approach as a contact killer, a feeding repellent, and an insect growth regulator that disrupts the nymph’s development. Unlike some other sprays, neem oil is not an instant killer, and repeated applications every seven to ten days may be necessary for sustained control.
Homeowners should prioritize the safety of beneficial insects, such as pollinators, by avoiding the application of any insecticide product to plants that are currently in bloom. These low-impact contact treatments have short residual activity, meaning they kill upon contact but do not remain active on the plant surface for long.