Being an adult moth is no picnic, UTEP research finds
Adult moths are more vulnerable to predation than moths in the caterpillar stage
image: Braulio Sanchez, a researcher and recent graduate of The University of Texas at El Paso, demonstrates caterpillar and adult moth replicas used in a study on moth predation. The study, recently published in the journal Insects, found that adult moths are more vulnerable to attack than they are when young.
Credit: The University of Texas at El Paso
EL PASO, Texas (July 1, 2025) – Age is just a number, or is it? A new study by UTEP researchers shows that adult moths are more vulnerable to attack than when they are young.
The recently published research in the journal Insects studied predation patterns for moths, a category of insects that undergoes metamorphosis. They found that compared to the caterpillar stage, adult white-lined sphinx moths face a much greater likelihood of predation.
Brett Seymoure, Ph.D., is an assistant professor of biological sciences at UTEP and the project’s principal investigator. He explained that holometabolous insects are those that undergo complete metamorphosis, starting life as an egg before moving on to the caterpillar stage, followed by the formation of a cocoon, or pupa, to transition to maturity and adulthood.
“There are multiple hypotheses about why these insects go through so many stages before reaching adulthood,” Seymoure said. “Our research set out to test the prediction that caterpillars are less likely to be attacked by predators, enabling the insect to survive to adulthood and reproduce before it has to face the most dangerous part of its life.”
Replicas of the white-lined sphinx moth in adult stage and caterpillar stage were built out of clay, said Braulio Alexis Sanchez, a postbaccalaureate student who conducted much of the research and was an undergraduate at the time of the study. The replica adult moth wings were made out of paper that was specially calibrated to have the exact color and appearance of real moth wings.
The replicas were then placed close together on creosote bushes at the Indio Mountains Research Station, a remote facility in West Texas that is owned by UTEP and used for biological and environmental research. Each day for three days, Sanchez and the research team checked the replicas at dawn and dusk and measured the number of bite marks, punctures and other signs of attack.
“Out of 70 replicas that were attacked, 50 were adults and 20 were caterpillars, and most of the attack marks were consistent with birds.” Sanchez said. “These results support our hypothesis that adult moths are more vulnerable to attack — and that predators are looking for a certain type of visual appearance when looking for food.”
Sanchez and Seymoure said the research is significant by demonstrating that different life stages have different survival pressures, which ultimately affect population dynamics.
“If moths in the caterpillar stage were more heavily-attacked, it would be much more difficult for moths to reach adulthood and reproduce,” Seymoure said.
Sanchez emphasized that many important functions on earth — and human survival —depend on insects.
Insects are both the most numerous and most diverse group of multi-cellular organisms on the planet, far outnumbering humans, birds, fish and other organisms by many orders of magnitude. And holometabolous insects ¾ including butterflies, moths, wasps and ants ¾ are the most numerous and diverse category of insect on Earth.
“Without insects, there are no humans, trees or plants,” he said. “Extensive study of insects is important to understand how to best support them and by extension, support all life on earth.”
The research was funded through UTEP’s College of Science, the Campus Office of Undergraduate Research Initiatives, as well as the NSF-funded ROADs program and Chihuahuan Desert Biodiversity Research Experience for Undergraduates.
Sanchez was recently selected for the Scientists in Parks internship, a program that places researchers in national parks throughout the nation to contribute to natural resource management. During the program, Sanchez will assess communities of plants, animals and insects in national parks throughout the Southwest, including Big Bend National Park, Guadalupe Mountains National Park and the Organ Mountains-Desert Peaks National Monument.
About The University of Texas at El Paso
The University of Texas at El Paso is America’s leading Hispanic-serving university. Located at the westernmost tip of Texas, where three states and two countries converge along the Rio Grande, 84% of our 25,000 students are Hispanic, and more than half are the first in their families to go to college. UTEP offers 171 bachelor’s, master’s and doctoral degree programs at the only open-access, top-tier research university in America.