A journey through the American West, one caterpillar at a time

Edith Chamberlain (she/her)
Hometown: Wenatchee, Washington
Major: Biology, '27
Internship: David Wagner (The University of Connecticut) in partnership with the Idaho Bureau of Land Management

Through the lens of some of nature’s least-appreciated creatures, Edith Chamberlain reflects on the West’s crisis of insect decline.

With the remarkable entomologist Dr. David Wagner and an ever-shifting team of botanists, insect experts, and scientists from the Idaho Bureau of Land Management, I’ve been spending the summer hunting for caterpillars throughout the American West, visiting numerous states and bushwhacking my way through some gorgeous country. Dr. Wagner has been working on a detailed 2500 page manuscript and separate field guide to caterpillars of the Western United States, a sort of sequel to his previous volume covering the East, and I have been lucky enough to get the chance to assist in this endeavor. Along with my co-intern Joe Hill (from the University of South Carolina), I have been collecting butterfly, moth, and sawfly larvae, photographing each individual, and making sure our ever-growing zoo of caterpillars remain alive and well. This work contributes to Dr. Wagner’s field guide, but more importantly, it provides data for the permanent scientific record, something becoming yet more crucial as insect biodiversity and total populations plummet.

Our work takes place throughout several states in the Western U.S., including Idaho, Oregon, Montana, and Arizona, across a wide variety of ecosystems. I’ve sampled spindly montane shrubs, herbaceous swamp plants, a plethora of coniferous trees, and countless others, exploring the western natural world through caterpillars and their host plants. A good understanding of caterpillars requires a good understanding of plants, as any given plant can give an entomologist loads of information about the animals dwelling upon it. The opposite is also true: As Dr. Wagner says, “caterpillars are the best botanists,” a reference to the fact that seemingly dissimilar plants supporting the same caterpillar species have turned out to be closely taxonomically related. The insects knew of this relation long before the biologists.

Another fact that these beautiful insects are well aware of is that the West is drying up. With every new location we visit, Dr. Wagner, who has been to many of our sites numerous times in past decades, makes a pained remark as to how dry everything is, how paltry the rains are compared to 20 years ago. This trend isn’t a fluke, it’s a sign of the aridification of the West, with unsustainable water use and climate change parching the land. Caterpillars are all surface area and minimal volume, making them particularly susceptible to drying out, which means that they have become much more difficult to find in areas where they were once abundant. Documenting these drops in population is critical, as it tells the story of the consequences of human activity. For certain species, the photos we capture for Dr. Wagner’s field guide may be the only way to see these animals in the future. In fact, Wagner often refers to himself as an elegist for these declining species, racing against time to tell their stories before they’re extinguished.

Caterpillars are often disregarded as simply being the drab precursors to much more beautiful butterflies and moths, but my summer work has shown me that these little worms are usually more attractive and always more interesting than their adult counterparts. Along with my newfound appreciation and knowledge of these creatures, I have gained a stronger urge to protect them, as I have seen the crucial role they play in the ecosystem. If caterpillars are no longer around, a crucial food source for birds has been lost. The hosts for parasitic pest-controlling flies and wasps are unavailable. A whole slew of pollinators is gone. These are only a few of the impacts of the catastrophic insect decline we’re experiencing. The ecosystem impacts of butterfly and moth decline are far-reaching and incredibly serious, and it is already too late for many species. However, with increased awareness and appreciation for insects, change can still be made to conserve and support what is left. Dr. Wagner’s field guide is one way to demonstrate the beauty, ecological significance, and fascinating life histories of hundreds of butterfly and moth species, and with knowledge often comes appreciation. Understanding and respecting our planet’s flora and fauna is the first step toward making meaningful change, and I am grateful to be one small part of this mission.