The spotted lanternfly, Lycorma delicatula, is an invasive planthopper from Asia that poses a serious threat to agriculture and forested ecosystems in the United States. This pest has a single generation each year and progresses through distinct developmental stages, known as instars, before reaching adulthood. Recognizing the immature forms is necessary for effective management and containment efforts, as these are the stages present for the majority of the growing season. The term “larvae” is often used colloquially to describe the four wingless nymphal stages that hatch from the overwintering egg masses. Correctly identifying these nymphs is the first step in protecting host plants and reporting new outbreaks.
Visual Characteristics of Instars 1-3
The initial three nymphal stages share a similar appearance, characterized by a uniform pattern. Upon hatching in the late spring, the first instar nymphs are small, measuring about one-eighth of an inch in length. Their entire body is covered in a solid black exoskeleton, heavily contrasted by bright white spots distributed across the head, thorax, and abdomen.
As the nymph feeds and grows, it molts into the second and third instars, but the overall color pattern remains unchanged. This black body with prominent white spots persists through the first three molts, with the primary difference being a slight increase in body size. By the third instar, the nymph may reach up to a quarter of an inch long. These early-stage nymphs are incapable of flight but are highly mobile planthoppers that move by rapidly crawling and jumping.
Visual Characteristics of the Fourth Instar
The fourth and final nymphal stage represents a shift in appearance, transitioning to a pattern of red and black. This final instar is larger than the preceding stages, growing up to one-half inch in length just before its final molt into an adult. The black base color remains, but the body now features large, vibrant patches of reddish-orange coloration.
The most noticeable change is the distinct red patches that cover the majority of the abdomen and the areas that will develop into the adult’s wings. The nymph retains the characteristic white spots, distributed across the red and black background. The contrast makes the fourth instar the most readily identifiable of the juvenile stages. Like the earlier instars, this final nymph stage is a proficient jumper used to move between feeding sites.
Seasonal Timing and Common Habitats
The appearance of spotted lanternfly nymphs is dependent on the season, with the four instars progressing sequentially from late spring through the end of summer. The first, second, and third instars are typically active from May through July, feeding on tender, new plant growth. During this early period, the young nymphs have a wide range of host plants, including various herbaceous plants and the soft stems of woody shrubs and trees.
As they develop into the fourth instar, their host preference begins to narrow, and this stage is most commonly observed from July into September. The larger nymphs and emerging adults increasingly favor woody plants such as grapevines, maple trees, fruit trees like apple and stone fruits, and especially the invasive Tree of Heaven (Ailanthus altissima).
Nymphs often aggregate in large groups on these preferred host plants, particularly concentrating on the newest growth where sap is most readily available. Their feeding activity causes them to excrete a sugary waste product known as honeydew, which can coat the plant and surrounding surfaces, promoting the growth of sooty mold.