Why dogs might be our best defense against spotted lanternflies

ITHACA, N.Y. — Man’s best friend may hold the key to stopping a devastating agricultural pest in its tracks — the invasive spotted lanternfly. That said, their superior detection abilities come with some surprising limitations, according to new research comparing canine and human detection methods.

Recent findings published in Ecosphere reveal that while specially trained detection dogs dramatically outperform human searchers in finding spotted lanternfly egg masses in forested areas, humans actually proved more effective at detecting the invasive pest in vineyards. These insights could reshape how we approach early detection of this destructive insect that threatens North America’s multi-billion dollar grape and wine industries.

“A spotted lanternfly infestation in a vineyard can cause 80% to 100% mortality of the vines in one growing season,” explains Angela Fuller, professor in the Department of Natural Resources and the Environment at Cornell University and lead author of the study, in a statement. This devastating impact is compounded by the need for increased pesticide use, with infestations resulting in a threefold increase in insecticide applications and cost increases of 170%.

First discovered in Pennsylvania in 2014, the spotted lanternfly has since spread to 18 states. The economic impact is substantial. In Pennsylvania alone, estimated losses range between $42.6 and $99.1 million for agricultural industries and between $152.6 and $263.3 million for forest industries. This planthopper feeds on at least 103 species of plants, posing a particular threat to grapes, fruit trees, and hops.

Researchers from Cornell University and partner organizations conducted field experiments across 20 vineyards in Pennsylvania and New Jersey to determine whether trained detection dogs could improve early detection of spotted lanternfly infestations compared to traditional human visual searches. The study focused on finding egg masses during winter and early spring when the insects are dormant but their egg masses remain attached to trees, vines, and other surfaces.

Two specially trained dogs — a Labrador Retriever and a Belgian Malinois — were trained initially on adult spotted lanternflies before spontaneously generalizing their detection skills to egg masses. The dogs and three human observers conducted searches along designated transects in both vineyard and forest settings. To ensure unbiased results, dogs and humans conducted their searches on different days to prevent human scents from influencing the canine detection work.

The results revealed distinct strengths for each detection method. In vineyards, human observers significantly outperformed their canine counterparts. “It was pretty easy for humans to see them, because they can do a systematic search, up and down a vine or pole,” Fuller explains. In these structured environments, humans detected approximately 31.4 egg masses per hour compared to dogs’ 24.0.

However, the situation reversed dramatically in forested areas, where dogs’ detection probability was more than three times higher than humans (51% vs. 15%). “The dogs find egg masses by smell,” Fuller notes. “So, in a very complex environment, it’s easier for a dog to smell something than it is for a human to see something that is small and cryptic.”

While both achieved similar efficiency rates in forests (humans: 7.66 detections/hour, dogs: 6.72/hour), dogs spent more time searching, resulting in more total detections. “The extra time that dogs take to find them is not as important as it is to find them in the first place, because you need to detect the egg masses in order to eradicate them,” notes Fuller.

The research yielded important insights about spotted lanternfly behavior and distribution. Occupancy probability was higher on vines within vineyards than in forests, and notably, occupancy declined with increasing distance from forests. The study found that egg masses were most likely to be found within 75 meters of forest boundaries, providing crucial guidance for focusing search efforts.

Weather conditions significantly influenced detection success. The study found that dogs’ detection probability improved with moderate winds, increasing from approximately 40% with no wind to about 60% with 16 km/h winds. However, deep snow posed challenges by limiting access to search areas and obstructing tree and vine bases where egg masses might be present.

While detection dogs require significant upfront investment in training and handling, their versatility offers unique advantages. The study dogs were also trained to detect several other invasive species, including Scotch broom, slender false brome, sticky sage, oak wilt, and kudzu, suggesting potential long-term value for comprehensive invasive species management programs.

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