Meant to Catch Spotted Lanternflies, Glue Traps Are a Horrifying Hazard for Birds

Aug 22, 2023

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Artist Sarah Valeri was on her way to an art studio open house in October when she stumbled across a grisly scene. Several trees lining the Brooklyn sidewalk were wrapped in strips of lime-green tape. Stuck to them were dead insects, feathers, and the carcasses of two birds. The horrifying centerpiece was a live Downy Woodpecker, splayed and writhing as it attempted to free itself from the sticky trap.

"It was awful," Valeri says, "I thought it was some gross art exhibit." She promptly cut down the tape and took the woodpecker to Wild Bird Fund, a local wildlife rehabilitation center. Despite the care it received there, the bird died a few days later.

The strips of tape were glue traps. Widely used to catch rodents or insects, the traps often capture snakes, bats, birds, and other unintended victims. In the past few years the method has become popular for catching the invasive spotted lanternfly. Entomologists started using them as a tool for monitoring lanternfly populations when the pests were first detected in Pennsylvania in 2014. But when the insects became widespread a few years later, the public began deploying the traps to help control the invasion. That's when experts noticed that lanternfly traps were ensnaring other wildlife like birds and small mammals—a problem they call "bycatch."

Do not try to remove a bird from a glue trap yourself—doing so risks further injury, the Wild Bird Fund warns. Instead, use paper towels or another non-adhesive material to cover the trap's sticky areas. Then remove the trap and place the whole bundle, including the bird, into a cardboard box, paper bag, or other ventilated container, and transport it to your local animal rehabilitator. Find a licensed rehabber near you at ahnow.org.

Native to Asia, spotted lanternflies are now found in at least 14 eastern states. In spring, lanternfly eggs hatch and the nymphs begin to feed on tender new growth. The nymphs go through four stages called instars, roughly doubling in size each time they molt into the next instar. Then, beginning around late July, the adults emerge. Later in the season, they often gather in the thousands, sucking sap from trees and raining a sugary excrement called honeydew on the foliage below, which can encourage the growth of sooty mold. The resulting damage often kills grapevines and non-native trees-of-heaven, and leaves many other plants vulnerable to pests and diseases.

To contain the spread, officials have urged the public to do whatever they can to kill the beautiful but destructive invaders. Beginning in 2018, researchers in Pennsylvania recommended glue traps as an effective tool for killing lanternflies, though they noted that birds, squirrels, and other wildlife might be harmed as an unintended consequence. The state's agricultural department also created programs that distributed the traps, while local hardware stores and garden centers stocked them on their shelves.

The bycatch victims then began to pour into wildlife centers, prompting the Lehigh Valley Audubon Society to collaborate and co-author a report with Pennsylvanian wildlife rehabilitators in 2021. The results, while not peer-reviewed or published, showed that glue-trap bycatch in the state reached an all-time high in 2020, with roughly 400 recorded cases. The victims included birds, bats, and flying squirrels. Around half were from species that forage on bark, and the vast majority were insect-eaters, likely attracted to the bugs in the traps. Only about 25 percent of the stuck animals were successfully released.

The traps’ adhesives aren't only a threat to dainty species: In 2021, a Red-tailed Hawk was admitted to Aark Wildlife Rehabilitation and Education Center near Philadelphia. "It was wrapped up like a package," says Susan Downes, the director of operations at the center. "It took me about two hours to get all the little pieces of tape off of him. It was just horrible." Despite the ordeal, the hawk was released from care after eight days of rest and recuperation. He was among the lucky ones; Downes says most birds perish from the overall stress of the experience. Many lose feathers and break bones while trying to free themselves from the powerful adhesives.

This concerning trend isn't isolated to Pennsylvania. Chris Soucy, director of the Raptor Trust in New Jersey, says at least 87 glue-trapped birds from several species—including White-breasted Nuthatch, Chipping Sparrow, and Barn Swallow—were admitted into his clinic in 2022 alone, a tenfold increase from the few rodent glue trap victims he received in previous years. In New York City, the woodpecker Valeri brought to Wild Bird Fund was the first lanternfly-trap case that clinic has treated.

"There's no real good reason to use this kind of trap," Soucy says. Birders and naturalists have documented birds eating lanternflies, making them a natural line of defense against the pest. "We’re killing the predators of the things we’re trying to kill," he says. "That's the wrong way to go about it."

As the morbid side effects of using glue traps to catch lanternflies became apparent, pest management specialists worked to develop a safer alternative: the circle trap. It's a modified version of a design originally used for the pecan weevil, another agricultural pest. The trap uses a flattened funnel that can be wrapped around an infested tree. "When lanternflies crawl up the tree, they’re basically crawling into a funnel and then being collected in the top," says Amy Korman, an entomologist and educator at Penn State Extension. The trap doesn't harm birds or other small animals, but may catch other insects.

Many environmental organizations have started sharing information about circle traps. For instance, NYC H2O created a DIY tutorial for building one with soccer cones, netting and plastic bags. Penn State Extension has its own circle trap how-to, along with other educational resources to help the public get involved in managing the pest, including how to put a screen on top of glue traps to make them safer for wildlife. Experts also encourage the public to squish lanternflies on sight or scrape their eggs off of trees, and to report sightings of the invaders.

Soucy hopes that through the Raptor Trust's efforts, such as publicizing instances of bycatch on social media, people will help prevent harm from glue traps and will seek other means of controlling lanternfly populations. "From my experience in this field, some of the really rewarding stuff we do is educational," he says. "These horrible, tragic things are 100 percent preventable."