Can Pet Dogs Be Trained to Sniff Out the Destructive Spotted Lanternfly Eggs?

A groundbreaking citizen science initiative, spearheaded by researchers from Texas Tech and Virginia Tech, is exploring the remarkable potential of pet dogs to locate the elusive and highly destructive egg masses of the spotted lanternfly (SLF). Dog trainer and author Melissa McCue-McGrath, a key participant in the study with her team of Maine-based dogs, provided insights into the project, highlighting both the successes and the inherent challenges of involving everyday canines in critical environmental conservation efforts. This novel approach could significantly bolster strategies to combat the spread of this invasive pest, which poses a substantial threat to agricultural industries and ecosystems across North America.

The Invasive Threat: Spotted Lanternfly

The spotted lanternfly ( Lycorma delicatula ) represents a severe ecological and economic threat, particularly to the agricultural sector in the United States. Originating from Asia, this planthopper was first detected in Pennsylvania in 2014, believed to have arrived on shipping crates alongside another invasive species, the Tree of Heaven ( Ailanthus altissima ). The Tree of Heaven, ironically named for its rapid growth and resilience, serves as the spotted lanternfly’s preferred host, providing an abundant food source that has facilitated its rapid establishment and spread.

What makes the spotted lanternfly particularly problematic is its broad diet and "opportunistic" egg-laying habits. Unlike highly specialized pests such as the emerald ash borer, which exclusively targets ash trees, the SLF feeds on over 70 different plant species. These include economically vital crops like hops, grapes, cherries, apples, and stone fruits, as well as native hardwood trees such as maple. As the lanternfly feeds, it excretes a sugary substance known as "honeydew." This sticky residue, while initially a mere nuisance, fosters the growth of black sooty mold. This mold then coats plants, inhibiting photosynthesis, weakening the plants, and ultimately leading to crop decimation. The cumulative economic impact on affected states, including Pennsylvania, New Jersey, New York, Maryland, Delaware, Virginia, West Virginia, Ohio, Connecticut, Massachusetts, and New Hampshire, is already significant, with potential losses estimated in the hundreds of millions, if not billions, of dollars annually if the pest continues its unchecked expansion.

The insect’s life cycle further complicates eradication efforts. After hatching in late spring (April to May), the nymphs progress through several instars before maturing into distinctive, brightly colored adults. These adults then lay eggs, typically in late summer and fall, which overwinter before hatching the following spring. Crucially, the egg masses are notoriously difficult to spot. They are often covered in a mud-like protective coating, blending seamlessly with surfaces like tree bark, rocks, outdoor furniture, and even vehicles. This camouflage, combined with their indiscriminate laying on almost any flat surface, makes them a primary vector for long-distance spread, as egg masses can hitchhike on cars, trains, and transported goods, effortlessly invading new territories. The impending threat to regions like southern Maine, just 20 minutes from the New Hampshire border where SLF has been established, underscores the urgency of effective detection methods.

Harnessing Canine Olfaction for Conservation

The idea of employing dogs for scent detection is not new; their extraordinary olfactory capabilities have long been utilized in various fields. Dogs possess up to 300 million olfactory receptors, compared to humans’ mere 6 million, and a much larger proportion of their brain is dedicated to analyzing scents. This allows them to detect odors at concentrations far below human perception. Their applications range from detecting explosives and illicit drugs to locating missing persons and identifying medical conditions like cancer and diabetes. In conservation, "conservation canines" are trained to find endangered species’ scat or detect invasive plants and animals, playing a vital role in ecological monitoring and protection.

The training methodology typically relies on associative learning, where a dog learns to associate a specific target odor with a highly rewarding reinforcer, such as food or a favorite toy. This process, often referred to as "pairing," conditions the dog to actively seek out and indicate the presence of the target scent. Melissa McCue-McGrath, a professional dog trainer and behavior consultant with extensive experience working with urban dogs, frequently incorporates scent work into her behavioral programs. She emphasizes its efficacy in building confidence, enhancing cognitive skills, and promoting relaxation, particularly in high-stress environments. Her background, though rooted in behavior rather than competitive scent work, proved invaluable for the citizen science project, as she adapted these principles to train pet dogs for a real-world conservation challenge.

A Unique Citizen Science Initiative

The project investigating canine detection of spotted lanternfly eggs emerged from a broader interest in how animals intersect with humanity, a topic McCue-McGrath explored in her podcast, "Bewilder Beasts." Inspired by stories of bees trained to detect bombs and honeybees inadvertently identifying the presence of SLF honeydew in Pennsylvania honey, McCue-McGrath recognized the potential for pet dogs to contribute. The multi-university study by Texas Tech and Virginia Tech sought to leverage this potential, specifically exploring if ordinary pet dogs, trained by their owners, could reliably find SLF egg masses during their daily walks.

The initiative was structured as a citizen science project, a collaborative effort that engages the public in scientific research. Citizen science offers numerous benefits, including the ability to collect vast amounts of data over large geographic areas at a relatively low cost, while also fostering public engagement and education in scientific processes. For McCue-McGrath, who learned about the study through one of her students, the concept immediately resonated. Despite her background being more in behavioral applications of scent work rather than competitive standards, she believed in the dogs’ innate ability. "If we can train bees to find a bomb in Croatia," she quipped, "I can train these five dogs or six dogs to find this egg mass."

The study aimed to recruit participants from various backgrounds, though it initially targeted handlers with experience in organizations like the National Association of Scent Work Dogs (NASW). McCue-McGrath’s team, which she affectionately called the "bad news bears" due to their focus on behavior cases rather than competitive prowess, nonetheless proved their capability. After an initial application process involving a "SeaBARK" personality and ability test for the dogs, her group was selected for the second cohort, receiving crucial funding and support for their participation.

Training and Overcoming Obstacles

The journey for McCue-McGrath’s team, comprising six dogs, was marked by significant logistical and environmental challenges, particularly given their location in Maine. Unlike their counterparts in warmer states like Virginia and Florida, the Maine team had to contend with a harsh winter. The dead spotted lanternfly eggs, provided by the researchers in small, window screen-like mesh packets, had to be distributed amidst a blizzard. McCue-McGrath recalled navigating icy roads, delivering the suspicious-looking packets in a "Pokemon lunchbox," and even encountering a school resource officer who questioned her presence and the contents of her box, highlighting the unusual nature of their scientific endeavor.

The initial training, despite the weather, demonstrated the dogs’ rapid learning capacity. Due to the blizzard, the first class was conducted via Zoom. McCue-McGrath’s 11-year-old daughter, acting as handler for their dog Captain, successfully got him "on odor" within just four trials. This involved the fundamental associative learning technique: pairing the distinct scent of the lanternfly eggs with a high-value reinforcer. For dogs already familiar with scent work, as most of McCue-McGrath’s dogs were, it was essentially an addition to their existing "scent Rolodex." They had previously learned to identify various essential oils like clove and birch, and the new "decaying matter" scent of the lanternfly eggs proved to be an instant favorite.

One notable participant was Woody, a Brittany spaniel with severe separation anxiety. Despite having only a month of scent work experience, Woody, a highly driven dog, quickly excelled. His handler, initially seeking behavioral solutions for his anxiety, found scent work to be a perfect outlet for his energy and keen sense of smell. McCue-McGrath advocated for Woody’s inclusion in the study, recognizing his untapped potential, and he quickly proved to be one of the most proficient detectors.

Field Trials and Real-World Application

The study involved a two-phase testing process: an Odor Recognition Test (ORT) and subsequent field trials. The ORT, to be completed within 14 weeks of receiving the eggs, required dogs to correctly identify the SLF eggs in one of six boxes. These boxes contained various distractors, including the mesh without eggs (to ensure they weren’t alerting to the metal), grass, and mulch. Dogs needed an 80% accuracy rate over ten trials to qualify for the field test. Four of McCue-McGrath’s dogs successfully passed the ORT, demonstrating their ability to distinguish the target odor. Captain, McCue-McGrath’s own dog, never formally took the ORT but later cleared the field courses, proving his detection ability.

The field trials presented a more complex challenge, simulating real-world search conditions. McCue-McGrath, mindful of her dogs’ behavioral needs, set up two 80-foot by 80-foot courses on her property: one in the woods and one in an open field. This flexibility accommodated dogs with aversions to specific environments—one dog disliked the woods after a negative experience with a stick, while another was too distracted by chipmunks in the field. Within four months, all participating dogs successfully completed their field trials, validating the "proof of concept" that pet dogs could be trained to detect SLF egg masses in varied outdoor settings.

However, the study also underscored the importance of handler advocacy and the behavioral well-being of the dogs. One student, whose dog June struggled with anxiety, faced significant hurdles during the ORT. An ice storm had disrupted power, forcing the team to relocate to an unfamiliar facility. In this new, scent-laden environment, June’s anxiety was exacerbated by a blaring fire truck horn during her test. Despite multiple attempts, her owner, observing June’s distress, made the compassionate decision to withdraw her from the formal study. Instead, they conducted a modified test where cheese was hidden, allowing June to successfully complete the exercise in a positive, confidence-building manner. This act of prioritizing the dog’s welfare over scientific completion highlights a crucial lesson for citizen science, especially when working with animals with behavioral histories. Remarkably, after a break, June returned to scent work and became one of the most reliable lanternfly hunters in McCue-McGrath’s classes, even using the lanternfly scent as a positive motivator to navigate agility obstacles in a new, potentially stressful environment.

The study also revealed a 40% attrition rate among the initial 180 citizen scientist participants. While the exact reasons are unknown, factors such as demanding schedules, environmental challenges, or simply the complexities of training may have contributed. However, the fact that 60% of participants persevered and demonstrated detection capabilities is a testament to the dedication of citizen scientists and the feasibility of the project. A fascinating observation from the study was that dogs in areas of live SLF invasion, when taking their field tests with dead eggs, often alerted to previously undetected live egg masses, confirming their ability to transition seamlessly between dead and live odors.

Expert Insights and Future Directions

McCue-McGrath emphasized that while the study demonstrates the immense potential of canine citizen science, it also comes with critical caveats. She cautions against individuals attempting to train their dogs on just "any old invasive species" without expert guidance. The brown-tailed moth, prevalent in Maine, serves as a stark example: its toxic hairs can cause severe rashes and respiratory issues, making it unsuitable for canine detection due to the risk of harm to the dog. The decision to focus on SLF eggs, rather than adults, was a carefully considered strategy developed in dialogue with plant, environmental, and dog scientists. Targeting eggs, which overwinter, offers the best chance to reduce the next generation of the pest before they can cause widespread damage.

Future applications could involve other invasive species, such as the emerald ash borer, another destructive pest. However, any such initiative must be developed in close consultation with environmental experts to ensure safety, efficacy, and to prevent accidental spread of the invasive species. The work often falls under the umbrella of "conservation canines" or "invasive species detection dogs," which operate with rigorous protocols and extensive training. Most of this specialized detection work is volunteer-based, requiring hundreds of hours of commitment from handlers and dogs to achieve operational competency, often focusing on specific targets like eggs or scat in challenging outdoor environments.

Beyond Detection: The Human Element in Dog Training

McCue-McGrath’s experiences in the spotted lanternfly study, as well as her two decades in dog training, are chronicled in her new book, Misadventures of the World’s Okayest Dog Trainer. The book offers a candid, behind-the-scenes look at the realities of the dog training profession, moving beyond idealized notions to explore the funny, heartbreaking, and often unexpected challenges trainers face. It delves into issues like sexism within the predominantly female industry (where 89.9% of graduates are women or non-binary individuals, yet systemic biases persist) and the complexities of dealing with difficult cases, from unexpected dog bites to hoarding situations.

The book, much like the citizen science project, highlights the profound bond between humans and dogs, and the dedication required from both species to achieve extraordinary feats. McCue-McGrath’s personal account of navigating the SLF study amidst significant personal challenges, alongside her students who also faced life crises, underscores the emotional investment inherent in such endeavors. The collective spirit, mutual support, and shared commitment to the scientific mission were as vital as any technical training.

In conclusion, the citizen science study on spotted lanternfly egg detection by pet dogs offers a promising avenue for environmental conservation. It demonstrates that with proper guidance, training, and a deep understanding of both canine behavior and ecological principles, everyday dogs and their dedicated guardians can play a crucial role in protecting natural resources and agricultural economies from invasive threats. This initiative not only contributes valuable data but also fosters a deeper connection between communities and the scientific challenges facing our planet.