The Spotted Lanternfly (SLF) is an invasive planthopper that threatens agricultural and ornamental plants across affected regions. Understanding the insect’s life cycle, particularly the moment of hatching, is important for effective management. The SLF overwinters solely in the egg stage. Locating and eliminating these masses before they hatch is the most effective way to prevent the destructive nymph and adult stages, marking the beginning of the insect’s most active phase.
The Critical Hatching Window
The Spotted Lanternfly eggs begin to hatch from late April through early May, highly dependent on environmental warmth. Hatching is an extended period that can last several weeks as temperature conditions are met across different microclimates. The emergence is triggered by the accumulation of warmth over time, which scientists measure using a metric called “degree-days.” This temperature-dependent development means the exact start date shifts yearly based on weather patterns. Nymphs require consistent temperatures above 13 degrees Celsius to develop and emerge successfully.
Identifying the Newly Hatched Nymphs
Immediately upon hatching, the Spotted Lanternfly enters the first of four nymphal stages, known as instars. These first-instar nymphs are very small, measuring only a few millimeters in length, or about the size of a tick. They are wingless but highly mobile and strong jumpers. Their bodies are entirely black and covered with bright white spots. They quickly scramble away from the egg mass, moving up the nearest vertical surface, such as a tree trunk, to find a suitable feeding location.
Progression Through Early Life Stages
After the first instar, the nymphs progress through three more stages before reaching adulthood, with each stage marked by a molt and an increase in size. The second and third instars maintain the black body with white spots, growing steadily, reaching up to about 3/8 of an inch long by the third stage. Active from May through July, their feeding intensity increases as they require more nutrients for growth. A significant visual transformation occurs in the fourth and final nymphal instar, which begins to appear around July. The insect is about half an inch long and develops a striking coloration: patches of bright red overlaid with black stripes and white spots. This pattern precedes the insect molting into its winged adult form, which appears from mid-July onward.
Locating the Egg Masses
The entire Spotted Lanternfly population overwinters as egg masses, laid by adult females from September until the first killing freeze. Each mass is approximately one inch long and contains 30 to 50 eggs, laid in segmented rows. The female covers the eggs with a waxy, putty-like secretion that is initially white but dries to a light grayish or mud-like color, helping to camouflage it against surfaces. These egg masses are commonly found on any flat, outdoor surface, demonstrating the insect’s adaptability. They are often deposited on tree bark, but can also be found on smooth, non-plant materials such as rocks, outdoor furniture, grills, boats, RVs, and vehicles.