The spotted lanternfly, an invasive insect native to Asia, was first identified in the United States in Pennsylvania in 2014. It has since spread to numerous states, impacting agriculture and natural ecosystems. Many people wonder when these destructive insects disappear for the season.
Understanding the Lanternfly Life Cycle
The life cycle of the spotted lanternfly spans a single year, beginning with overwintering egg masses. These egg masses hatch into nymphs, which undergo four distinct developmental stages, known as instars, before reaching adulthood. The first three nymphal instars are black with white spots and are active from May through July. They primarily feed on a wide range of plants, including tree of heaven, willow, and maple.
The fourth instar nymphs are red with white and black spots, and are active from July through mid-August. Following this stage, nymphs molt into their adult form, which can be found from July through December. Adults are approximately one inch long with black-spotted, pinkish-tan forewings and striking red hindwings that are visible during flight.
When Adult Lanternflies Disappear
Adult spotted lanternflies do not survive the colder months. These adults typically die off with the first hard frosts of late autumn or early winter, usually between late October and December, depending on the specific geographical location.
Adult female lanternflies engage in egg-laying from September through November, or until the first killing freeze. These egg masses are laid on various outdoor surfaces and are covered with a protective, mud-like substance that allows them to overwinter successfully. While the adult population perishes, the next generation remains dormant, waiting for warmer temperatures to hatch in the spring.
Managing Lanternflies During Their Active Season
During warmer months, several strategies can help manage spotted lanternfly populations. From May to July, when nymphs are black with white spots, sticky bands can be placed around tree trunks to trap them as they move up and down. These bands should be properly installed with a barrier to prevent the capture of non-target species such as birds. Squashing nymphs and adults upon sight is also an effective immediate intervention, particularly when populations are low.
When populations are higher, contact insecticides, such as bifenthrin, carbaryl, or malathion, can be used as spot treatments against nymphs and adults. Horticultural oils and insecticidal soaps also provide control, though they may require repeated applications due to the insects’ mobility. For prolonged protection, systemic insecticides like dinotefuran or imidacloprid can be applied as trunk sprays, injections, or soil drenches.
Preventing Next Year’s Infestation
Once adult lanternflies have perished, preventing the next generation involves targeting their overwintering egg masses. Egg masses can be found from September through June, making late fall, winter, and early spring ideal times for removal. These masses are typically one to one-and-a-half inches long and appear as light grayish splotches of mud or cement on various surfaces, including tree trunks, rocks, outdoor furniture, and vehicles.
To destroy egg masses, scrape them off surfaces using a credit card, putty knife, or similar tool. Place scraped eggs into a plastic bag containing rubbing alcohol or hand sanitizer to ensure they are killed, as simply scraping them to the ground may not be sufficient. Inspect outdoor items and vehicles before moving them to prevent the accidental spread of egg masses to new locations.