The invasive spotted lanternfly (Lycorma delicatula) lays its eggs in masses, which often resemble splotches of mud, on tree limbs and trunks. A study in Pennsylvania finds that putting infested wood through a wood chipper effectively destroys spotted lanternfly egg masses, and researchers recommend the practice for reducing the potential spread of the pest. (Photo credit: Kenneth R. Law, USDA APHIS PPQ, Bugwood.org)

As the invasive spotted lanternfly (Lycorma delicatula) has begun to spread in the eastern United States, entomologists, pest management professionals, and government agencies have gone into high gear in an effort to stop it before it marches across the country.

While enlisting the public’s help in spotting and reporting the pest, research is also underway to examine its biology and behavior and the management practices that will aid in preventing its spread. Because the spotted lanternfly’s primary target is Tree of Heaven (Ailanthus altissima)—though it will also feed more than 70 other plant species, including grapes, hops, and fruit trees—one of the first questions asked was how infested wood should best be handled.

A study published this month in the open-access Journal of Insect Science provides an official answer: chipping.

The spotted lanternfly lays its eggs in small masses, which resemble splotches of mud, often on tree trunks and limbs. In 2015, shortly after the invasive insect was first discovered in Berks County, Pennsylvania, researchers at the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (USDA-APHIS) and the Pennsylvania Department of Agriculture began a study on whether putting infested woody debris through a wood chipper would destroy spotted lanternfly egg masses.

The results were clear: In 11 trees’ worth of woody debris infested with spotted lanternfly egg masses, not a single nymph emerged after chipping.

The wood was chipped with a high-speed, 12-inch disc chipper set to produce 1-by-1-inch chips, the USDA-APHIS standard that is also recommended in management programs for the Asian longhorned beetle (Anoplophora glabripennis) and emerald ash borer (Agrilus planipennis).

“This study … has proven quite conclusively that soft-bodied insect life stages do not survive standard high-speed chipping process,” says Ron Mack, commodity treatment specialist at USDA-APHIS and a co-author on the study.

First encountered in the United States in Pennsylvania in 2014, the spotted lanternfly (Lycorma delicatula) had spread to New York, Delaware, and Virginia by early 2018. The invasive insect threatens Tree of Heaven as well as grapes, hops, and fruit trees, and it has a penchant for hitchhiking. Anyone sighting spotted lanternfly is urged to report it to their state agriculture department or local extension office. (Photo credit: Lawrence Barringer, Pennsylvania Department of Agriculture, Bugwood.org)

After chipping the infested wood, the researchers placed the chips in barrels and observed them for 15 weeks to see if and when any spotted lanternfly nymphs would emerge. By comparison, control barrels, with unchipped branches and an average of 34 egg masses each, produced an average of 559 nymphs.

Sven-Erik Spichiger, entomology program manager at the Pennsylvania Department of Agriculture and a co-author on the study, says chipping infested wood is one part of a broader set of management efforts for spotted lanternfly, one targeted specifically at the egg stage of the insect’s development.

“When these points in the insect’s life cycle occur are highly variable, so chipping is advised year-round to be safe,” he says.

Research on many other aspects of the spotted lanternfly (SLF) continues, says Miriam Cooperband, Ph.D., entomologist at USDA-APHIS and lead author on the study. “My research on SLF focuses mainly on gaining a better understanding of the biology and host range of SLF, their dispersal capabilities, investigating semiochemicals that are used to find host plants and/or mates, and development of lures and traps,” she says. “Research on control would be helpful because the tools available at this time are quite limited. But to do that, we need more basic biology research as well.”

Cooperband also notes the public’s role in remaining vigilant, as well. “Community involvement has been exceptional in the fight against SLF in eastern Pennsylvania, and this enthusiasm has greatly helped everyone involved do their jobs.”