The Spotted Lanternfly (SLF), Lycorma delicatula, is an invasive planthopper that poses a significant threat to agricultural crops and forest health across the United States. This pest damages plants by feeding on sap and excreting honeydew. Understanding the visual progression of the juvenile stages is important for early identification and control efforts. The SLF undergoes a dramatic transformation across its four nymphal stages, each presenting a distinct appearance that helps in tracking its life cycle.
The Initial Nymph Stages (Black and White)
The first three juvenile stages, known as instars, are small, wingless, and feature a solid black body with bright white spots. When they first hatch in late spring, the first instars are tiny, measuring only about one-eighth to one-quarter of an inch long. They are occasionally mistaken for ticks due to their size. As they progress through the second and third instars in early to mid-summer, they retain this black-and-white coloration but grow slightly larger with each molt.
These early-stage nymphs are strong jumpers, which is their primary defense mechanism since they are incapable of flight. They are most commonly found feeding on the tender, new growth of various plants, including grapevines and several types of trees. This phase lasts from approximately May through July, and their small size makes them challenging to detect.
The Late-Stage Nymph (Red, Black, and White)
The fourth and final nymphal stage is marked by a striking change in coloration, making it the most visually recognizable juvenile form. Starting around July and lasting into September, the nymph develops prominent red patches across its body. This red contrasts with the familiar black background and distinct white spots. This final stage is considerably larger than the earlier instars, reaching a length of about a half-inch to three-quarters of an inch before maturing.
The vibrant red coloring acts as a warning signal to potential predators, indicating the insect may be unpleasant to eat. During this time, the fourth-instar nymphs are highly active and continue to feed heavily on a wide variety of plants, often congregating in large numbers. Their feeding behavior is particularly damaging as they begin to target the woody parts of plants, such as tree trunks and branches.
The Adult Form and Action Steps
Following the final molt, the insect transforms into the adult Spotted Lanternfly, which appears starting in July and persists through the first killing frost. The adult is roughly one inch long with a tent-like posture when at rest, displaying grayish-tan forewings covered in black spots. When startled, the insect reveals its brightly colored hindwings, which are a combination of scarlet red, black, and white bands.
If any life stage of the Spotted Lanternfly is discovered, immediate action should be taken to prevent its spread. The first step is to kill the insect by stomping or crushing it, as both the nymphs and adults are easily destroyed. After the pest is eliminated, report the sighting to the state or local agricultural extension office, especially if the location is outside of an already quarantined area. This reporting process helps officials track the pest’s movement and implement targeted control measures.