In the battle against the aggressive insect known as the spotted lanternfly—which threatens trees, crops, and other agricultural products—Virginia has gained a new ally. A research team led by Assistant Professor Scotty Yang from the Department of Entomology in Virginia Tech's College of Agriculture and Life Sciences has discovered that ants can be used to determine whether spotted lanternflies have invaded new areas. The findings were published in the journals Pest Management Science and Neobiota.

Native to Asia, the spotted lanternfly was introduced to the United States in 2014 and has since spread rapidly, damaging vineyards, ornamental trees, and backyard gardens. They feed by piercing plants with straw-like mouthparts to suck sap, leaving behind sugary honeydew that contains insect DNA and creates a sticky mess. Ants are attracted to this honeydew; they seek it out, consume it, and carry it back to their nests to share.

Scotty Yang wondered whether ants collecting honeydew could serve as an early warning system for spotted lanternflies. Research confirmed that the answer is yes. Ants foraging in areas infested with spotted lanternflies carry traces of the pest's DNA in their bodies. By analyzing ants in the laboratory, scientists can reliably detect the presence of spotted lanternflies in an area even without directly observing the insects.

The research team employed an "environmental DNA detection" approach: spotted lanternflies leave tiny DNA fragments in the honeydew they excrete. After collecting ants, polymerase chain reaction (PCR) analysis of the DNA inside them can identify minute amounts unique to the lanternfly. Professor Yang's team developed a new "antDNA" method that is accurate and effective—an ant that has consumed a single meal of spotted lanternfly honeydew still carries the pest's DNA five days later. Because ants have a wide foraging range, they can detect lanternflies up to 100 meters away from known infestation sites.

Early detection of the spotted lanternfly is critical. It poses a serious threat to economically important crops, feeding on a wide variety of plants and weakening them in the process. The honeydew also promotes the growth of sooty mold, causing further harm. Once established, eradication requires multiple methods, and early discovery is the best option.

Current detection relies on visual identification of the insects or egg masses by humans—a challenging task before they become abundant, when they are even harder to control. The new method, which simply involves collecting ants and testing for DNA, saves time and money while protecting host plant health. Professor Yang noted that ants are nearly ubiquitous and serve as ideal frontline samples for collecting spotted lanternfly DNA. The method is not limited by habitat, and ant collection techniques are well-established and easy to scale.

Moreover, Professor Yang's research extends beyond the spotted lanternfly—any insect that secretes honeydew and leaves DNA behind could potentially be tracked, enabling earlier and smarter protection of crops, forests, and natural ecosystems. Currently, Professor Yang's team is developing a field-ready antDNA kit that allows on-site molecular analysis for faster results and real-time tracking and response to new invasions.