The Spotted Lanternfly (SLF), an invasive planthopper from Asia, presents a significant threat to agriculture and natural ecosystems across North America. Its life cycle includes four distinct nymphal stages, or instars, before it matures into an adult. Identifying these young, flightless stages is important for effective control, as their appearance changes dramatically before the final molt. Early detection and elimination of these nymphs is a primary strategy in limiting the spread of this pest.
Early Nymphs: The Black and White Stages
The first three nymphal stages of the Spotted Lanternfly share a consistent and recognizable color pattern, which is displayed from roughly May through July. Newly hatched nymphs, known as first instars, are quite small, measuring only about one-eighth of an inch long, roughly the size of a pencil eraser tip. Their bodies are entirely black, but they are covered with bright white spots. This combination of colors helps them camouflage against the bark of certain trees.
The nymphs grow larger as they progress through the second and third instars, shedding their exoskeleton in a process called molting, but they maintain the same black and white coloration. By the third instar, the insect is noticeably larger, reaching approximately one-quarter of an inch in length. These early stages are flightless, but they are highly mobile, relying on walking and powerful jumping to move between feeding sites. Their piercing-sucking mouthparts are not yet strong enough to penetrate thick, woody tissue, so they focus their feeding on the tender, new growth of plants.
The Red Warning: Appearance of the Final Nymph Stage
A transformation occurs when the insect enters its fourth and final nymphal stage, typically appearing from July through mid-August. This stage is visually distinct and signals the imminent transition to the adult form. The black base color remains, along with the white spots, but the body develops conspicuous patches of brilliant red. This final nymph is the largest of the juvenile stages, growing up to three-quarters of an inch long before its final molt. The combination of red, black, and white serves as a warning coloration to deter predators. The fourth instar feeds more aggressively than the earlier stages and its body shape begins to look more robust, preparing for the development of wings.
Where Nymphs Are Found and How They Behave
Spotted Lanternfly nymphs are generalist feeders, meaning they can be found on a broad range of plants. Early instars have a wide host range and are often found feeding on the soft, succulent shoots and herbaceous plants, as their mouthparts are not developed enough to pierce woody bark. As they mature, the nymphs begin to gravitate toward woody plants and trees, including economically significant species like grapevines and fruit trees. The invasive Tree of Heaven (Ailanthus altissima) is a preferred host tree, especially for the later nymphal stages.
Nymphs tend to congregate in large numbers on their host plants, where they feed by sucking sap from the phloem tissue. When disturbed, these flightless pests exhibit a characteristic behavior: they move rapidly and launch themselves away with a powerful jump. This jumping ability is their primary defense and method of rapid local movement. They are often easiest to spot at dusk or at night when they migrate up and down the trunks of trees.