David Wagner, Ph.D.

Professor of Ecology and Evolutionary Behavior University of Connecticut

  • Storrs CT

Professor Wagner is an expert in caterpillars, butterflies, moths, insect conservation, global insect decline

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Spotlight

3 min

Moths in the Mojave, with UConn's David Wagner

Did you know that there are approximately 180,000 moth and butterfly species living in California’s Mojave Desert? Moths, the winged insects famous for eating sweaters and flocking to lights at night, are a mysterious and captivating species for entomologists like UConn's David Wagner. He was part of a research study that was documented recently in The Washington Post. Each night in the desert, vast clouds of sphinx moths, some spanning the palm of your hand, speed between night-blooming flowers, sipping nectar. Ethmia, tiny black moths with spots shaped like musical notes, emerge from the dark like fairies. Thousands of geometrid moths, no bigger than your fingernail, slip by cloaked in desert hues from rusty reds to pale green. To witness them, I traveled deep into the Mojave Desert this spring with a team from the California Academy of Sciences working to ensure the survival of lepidoptera. For two days, we beat bushes, placed traps and collected thousands of moths to see what lives there — and what can be saved. Moths have inhabited our planet for at least 200 million years. But the conservation status of about 99 percent of moth species remains unknown. Some, like sphinx moths, remain abundant. Many others are probably being pushed to the brink by development, land-use changes, pesticides and pollution, and rising temperatures. “It’s not this unseen force,” says David Wagner, an entomologist at the University of Connecticut. “It’s humans.” Over two nights in the desert, I discovered just how easy it is to fall in love with an unloved insect. And why “mothing” may be the best way to discover the miracle of biodiversity in your own backyard. On the arid western edge of the Mojave, where the desert floor rises to meet the San Bernardino Mountains, sits the 306-acre Burns Piñon Ridge Reserve. We venture out in the morning with beating sticks. Hitting the branches of small oaks and rabbitbrush deposits a treasure trove of insect life into collectors made out of fabric: Crane flies, green lacewings, spiders, walking sticks and caterpillars that will one day grow into moths. Wagner and Chris Grinter, an entomologist and collection manager at the California Academy of Sciences, will catalogue the most interesting ones. The academy houses a collection of 18 million insects, 700,000 of which are butterflies and moth specimens. Many are still waiting for scientists to identify and name them. The plight of moths and caterpillars has fascinated Wagner since childhood. After 20 years, he is no less enthusiastic — or worried. Wagner traveled to Burns Piñon to help finish his magnum opus, the successor to his 500-page guide to eastern North America’s caterpillars. The guide for the west will probably run more than 1,500 pages, a testament to the region’s remarkable biodiversity. As the sun sets, the mood is anticipatory. We head out into the desert to set our traps and see what moths we’ll discover. “The nice thing,” says Grinter, “is moths will come to you.”  The article is an amazing read and the link is above. And if you are interested in knowing more about moths, insects, or the fascinating field of entomology, then let us help. Dr. David Wagner is an expert in caterpillars, butterflies, moths, and insect conservation, and he's commented extensively on the current decline of insects worldwide. Click his icon to arrange an interview today.

David Wagner, Ph.D.

2 min

UConn insect expert David Wagner on the troubling decline of the mayfly

One of the world's oldest flying insects is in trouble. Mayflies are in serious decline and, after 300 million years in existence, their dwindling population should be an alarm bell for all of us. More than just a bug with a short life span flying masterfully near creeks, rivers, and ponds, the mayfly plays a serious role in local ecosystems and the environment at large. A key component in the food chain, the mayfly nymph feeds off of algae, plants, and rotting leaves, cleaning up nature's mess while growing large enough to become a meal itself -for fish, amphibians, lizards, birds, and even humans. Without mayflies, the ripple effect upwards could mean calamity for the planet. In a recent Washington Post Magazine deep-dive, UConn insect expert David Wagner offered his perspective on the on the plight of the mayfly: I reached out to David Wagner, a biologist and lepidopterist at the University of Connecticut, for context, thinking that perhaps the problems were isolated or overblown. He has studied insects for decades and reviewed numerous scientific studies about them from around the globe. He did not provide much comfort. There’s a growing body of research suggesting that the world is in the midst of its sixth mass extinction, he said. The losses of all kinds of creatures appear to be driven by climate change, habitat degradation, pollution and other ecological stressors. In a paper for the Proceedings of the National Academy of Sciences last year, “Insect Decline in the Anthropocene: Death by a Thousand Cuts,” Wagner and several other scientists delivered a stark warning about the disappearance of insects. The report did not focus on mayflies, but Wagner told me they are among the most vulnerable of the world’s insects because of their need for clean, well-oxygenated water. “Mayflies are reliable ‘canaries in the coal mines’ for freshwater systems,” he explained. “And their future prospects, especially in areas that are drying or warming, are bleak.” September 19 Washington Post Magazine Dr. David Wagner is an expert in caterpillars, butterflies, moths, and insect conservation, and he's commented extensively on the current decline of insects worldwide. Click his icon to arrange an interview today.

David Wagner, Ph.D.

1 min

"Apocalypse" - A period of mass extinction threatens insects – and the world that depends on them

UConn entomologist and professor David Wagner says all kinds of insects are at risk for “a death by a thousand cuts" -decline attributed to multiple factors, including the climate crisis, agricultural intensification, development, deforestation, and the introduction of exotic and invasive species into new environments. He discusses the threats to the world's insect populations in this compelling new video report from UConn Today: Wagner cautions that many of these creatures will not be with us for much longer, and says people must act swiftly to help prevent these tremendous losses before it is too late. Wagner remains hopeful, and says there are many actions that can be taken now — from encouraging political leaders to enact policy changes, to simply letting part of the front lawn grow freely to provide a food-rich environment for insects. “This planet isn’t here for us to exploit,” Wagner says. Dr. David Wagner is an expert in caterpillars, butterflies, moths, insect conservation, and global insect decline, and he’s available to speak with media. Simply click on his icon now to arrange an interview today.

David Wagner, Ph.D.
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Biography

Professor Wagner's research focuses on entomology -- insect anatomy, behavior, biology, development, diversity, ecology, evolution, and physiology. He has studied ghost moths (Hepialidae), several families of leafminers, and Noctuidae. Over the past decade Wagner has taken a special interest in the immature stages and life histories on caterpillars. Wagner has a deep interest in matters relating to insect conservation. He completed work on a butterfly atlas for the State of Connecticut and a review article on threats posed to rare or endangered insects by non-native species.

Areas of Expertise

Butterflies and Moths
Caterpillars
Entomology
Invasive Species Impacts
Insects

Education

Univeristy of California - Berkeley

Ph.D.

Entomology

Colorado State University

B.S.

Plant Pathology and Botany

Social

Media Appearances

‘Half the tree of life’: ecologists’ horror as nature reserves are emptied of insects

The Guardian  online

2025-06-03

When David Wagner stepped out into the US’s southern wilderness this spring, he found landscapes emptied of life. The entomologist has devoted much of his career to documenting the vast diversity of US insect life, particularly rare caterpillars. He traverses the country to find specimens, often on long road trips searching for caterpillars by day and moths by night.

Now, he finds himself coming home empty-handed. “I just got back from Texas, and it was the most unsuccessful trip I’ve ever taken,” he says. “There just wasn’t any insect life to speak of.”

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Butterflies in the U.S. are disappearing at a ‘catastrophic’ rate

The Washington Post  print

2025-03-06

David Wagner, a University of Connecticut entomologist not involved in the study, said butterflies act as a “yardstick for measuring what is happening” among insects broadly. He called the new findings “catastrophic and saddening.”

“The study is a much-needed, Herculean assessment,” he wrote in an email. “The tree of life is being denuded at unprecedented rates. I find it deeply disheartening. We can and must do better.”

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Why you just might fall in love with moths

The Washington Post  online

2024-10-29

Moths have inhabited our planet for at least 200 million years. But the conservation status of about 99 percent of moth species remains unknown.

Some, like sphinx moths, remain abundant. Many others are probably being pushed to the brink by development, land-use changes, pesticides and pollution, and rising temperatures. “It’s not this unseen force,” says David Wagner, an entomologist at the University of Connecticut. “It’s humans.”

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Articles

The global distribution of diet breadth in insect herbivores

Proceedings of the National Academy of Sciences

2015

Understanding variation in resource specialization is important for progress on issues that include coevolution, community assembly, ecosystem processes, and the latitudinal gradient of species richness. Herbivorous insects are useful models for studying resource specialization, and the interaction between plants and herbivorous insects is one of the most common and consequential ecological associations on the planet.

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Climate change impacts on bumblebees converge across continents

Science

2015

For many species, geographical ranges are expanding toward the poles in response to climate change, while remaining stable along range edges nearest the equator. Using long-term observations across Europe and North America over 110 years, we tested for climate change–related range shifts in bumblebee species across the full extents of their latitudinal and thermal limits and movements along elevation gradients.

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Historical changes in northeastern US bee pollinators related to shared ecological traits

Proceedings of the National Academy of Sciences

2013

Pollinators such as bees are essential to the functioning of terrestrial ecosystems. However, despite concerns about a global pollinator crisis, long-term data on the status of bee species are limited. We present a long-term study of relative rates of change for an entire regional bee fauna in the northeastern United States, based on >30,000 museum records representing 438 species.

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