The outlook for butterflies in the U.S. appears as fragile as their delicate wings. A study published in shows that the population of 554 species of butterflies plunged by 22% from 2000 to 2020.
Just 3% of the most commonly observed butterflies saw an increase in population. Invasive species, as well as native butterflies, have suffered, according to the study.
Theresa Dellinger, an entomologist and diagnostician at the Insect Identification Lab at Virginia Tech, told WTOP that, “Unfortunately, this is applying to most of the species that I looked at, which included everything from our common species like the Monarch butterfly to even some pest species like the Cabbage White butterfly that’s commonly seen attacking vegetables in the garden.”
The Cabbage White butterfly is an invasive species that first appeared in North America in the mid-19th century.
Dellinger said one factor that’s causing the decline in populations is habitat loss.
“Enough where we have less places for butterflies to develop” in their caterpillar stage, “and as the adults are looking for food sources,” Dellinger said.
Pesticide use is also contributing to the drop in butterfly populations, she said.
“And we’re seeing competition from invasive plant species that compete against the host species that the butterflies use,” she said.
Even without the stressors of habitat loss, pesticide use and climate change, Dellinger said butterflies face challenges throughout their life cycle, including as caterpillars.
“We have a lot of birds that come into the area to eat those caterpillars very early in the spring, and then you have things like other insects, frogs, lizards, and they’re all feeding on insects as well, including those caterpillars,” she said.
Dellinger said there are a number of ways that homeowners can
One suggestion, she said, is by “encouraging native plants over imported invasive species in their yards,” and cutting back on pesticide use.
“If homeowners have questions about how they can do butterfly-friendly habitats, or encourage local populations of insects, I highly recommend they reach out to their local master gardener or master naturalist for more information,” Dellinger said.
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