The Invading Sea
  • News
  • Commentary
  • Multimedia
  • Public opinion
  • About
No Result
View All Result
The Invading Sea
  • News
  • Commentary
  • Multimedia
  • Public opinion
  • About
No Result
View All Result
The Invading Sea
No Result
View All Result

Butterflies declined by 22% in just 2 decades across the US – there are ways you can help save them

Habitat loss, insecticides, rising temperatures and drying landscapes can all harm these fragile insects

by Eliza Grames
March 12, 2025
in Commentary
0

By Eliza Grames, Binghamton University, State University of New York

If the joy of seeing butterflies seems increasingly rare these days, it isn’t your imagination.

A tropical queen butterfly at Arthur Marshall Loxahatchee National Wildlife Refuge in Boynton Beach (Judy Gallagher, CC BY 2.0, via Wikimedia Commons)
A tropical queen butterfly, one of the species that has seen a steep decline (Judy Gallagher, CC BY 2.0, via Wikimedia Commons)

From 2000 to 2020, the number of butterflies fell by 22% across the continental United States. That’s 1 in 5 butterflies lost. The findings are from an analysis just published in the journal Science by the U.S. Geological Survey’s Powell Center Status of Butterflies of the United States Working Group, which I am involved in.

We found declines in just about every region of the continental U.S. and across almost all butterfly species.

Overall, nearly one-third of the 342 butterfly species we were able to study declined by more than half. Twenty-two species fell by more than 90%. Only nine actually increased in numbers.

Some species’ numbers are dropping faster than others. The West Coast lady, a fairly widespread species across the western U.S., dropped by 80% in 20 years. Given everything we know about its biology, it should be doing fine – it has a wide range and feeds on a variety of plants. Yet, its numbers are absolutely tanking across its range.

Why care about butterflies?

Butterflies are beautiful. They inspire people, from art to literature and poetry. They deserve to exist simply for the sake of existing. They are also important for ecosystem function.

How U.S. butterfly populations changed by region, 2000-2020 (Chart: The Conversation, CC-BY-ND; Source: Colin Edwards, et al., Science 2025)
How U.S. butterfly populations changed by region, 2000-2020 (Chart: The Conversation, CC-BY-ND; Source: Colin Edwards, et al., Science 2025)

Butterflies are pollinators, picking up pollen on their legs and bodies as they feed on nectar from one flower and carrying it to the next. In their caterpillar stage, they also play an important role as herbivores, keeping plant growth in check.

Butterflies can also serve as an indicator species that can warn of threats and trends in other insects. Because humans are fond of butterflies, it’s easy to get volunteers to participate in surveys to count them.

The annual North American Butterfly Association Fourth of July Count is an example and one we used in the analysis. The same kind of nationwide monitoring by amateur naturalists doesn’t exist for less charismatic insects such as walking sticks.

What’s causing butterflies to decline?

Butterfly populations can decline for a number of reasons. Habitat loss, insecticides, rising temperatures and drying landscapes can all harm these fragile insects.

A study published in 2024 found that a change in insecticide use was a major factor in driving butterfly declines in the Midwest over 17 years. The authors, many of whom were also part of the current study, noted that the drop coincided with a shift to using seeds with prophylactic insecticides, rather than only spraying crops after an infestation.

The California tortoiseshell butterfly can look like wood when its wings are closed, but they’re a soft orange on the other side. (Walter Siegmund/Wikimedia Commons, CC BY-SA)
The California tortoiseshell butterfly can look like wood when its wings are closed, but they’re a soft orange on the other side. (Walter Siegmund/Wikimedia Commons, CC BY-SA)

The Southwest saw the greatest drops in butterfly abundance of any region. As that region heats up and dries out, the changing climate may be driving some of the butterfly decline there. Butterflies have a high surface-to-volume ratio – they don’t hold much moisture – so they can easily become desiccated in dry conditions. Drought can also harm the plants that butterflies rely on.

Only the Pacific Northwest didn’t lose butterfly population on average. This trend was largely driven by an irruptive species, meaning one with extremely high abundance in some years – the California tortoiseshell. When this species was excluded from the analyses, trends in the Pacific Northwest were similar to other regions.

When we looked at each species by its historical range, we found something else interesting.

Many species suffered their highest losses at the southern ends of their ranges, while the northern losses generally weren’t as severe. While we could not link drivers to trends directly, the reason for this pattern might involve climate change, or greater exposure to agriculture with insecticides in southern areas, or it may be a combination of many stressors.

There is hope for populations to recover

Some butterfly species can have multiple generations per year, and depending on the environmental conditions, the number of generations can vary between years.

This gives me a bit of hope when it comes to butterfly conservation. Because they have such short generation times, even small conservation steps can make a big difference and we can see populations bounce back.

The Karner blue is an example. It’s a small, endangered butterfly that depends on oak savannas and pine barren ecosystems. These habitats are uncommon and require management, especially prescribed burning, to maintain. With restoration efforts, one Karner blue population in the Albany Pine Bush Preserve in New York rebounded from a few hundred individuals in the early 1990s to thousands of butterflies.

Similar management and restoration efforts could help other rare and declining butterflies to recover.

What you can do to help butterflies recover

The magnitude and rate of biodiversity loss in the world right now can make one feel helpless. But while national and international efforts are needed to address the crisis, you can also take small actions that can have quick benefits, starting in your own backyard.

A patch of wildflowers and grasses can become a butterfly garden, like this one in Townsend, Tenn. (Chris Light, CC BY-SA)
A patch of wildflowers and grasses can become a butterfly garden, like this one in Townsend, Tenn. (Chris Light, CC BY-SA)

Butterflies love wildflowers, and planting native wildflowers can benefit many butterfly species. The Xerces Society for Invertebrate Conservation has guides recommending which native species are best to plant in which parts of the country. Letting grass grow can help, even if it’s just a strip of grass and wildflowers a couple of feet wide at the back of the yard.

Supporting policies that benefit conservation can also help. In some states, insects aren’t considered wildlife, so state wildlife agencies have their hands tied when it comes to working on butterfly conservation. But those laws could be changed.

The federal Endangered Species Act can also help. The law mandates that the government maintain habitat for listed species. The U.S. Fish and Wildlife Service in December 2024 recommended listing the monarch butterfly as a threatened species. With the new study, we now have population trends for more than half of all U.S. butterfly species, including many that likely should be considered for listing.

With so many species needing help, it can be difficult to know where to start. But the new data can help concentrate conservation efforts on those species at the highest risk.

I believe this study should be a wake-up call about the need to better protect butterflies and other insects – “the little things that run the world.”The Conversation

Eliza Grames is an assistant professor of biological sciences at Binghamton University, State University of New York.

This article is republished from The Conversation under a Creative Commons license. Read the original article. Banner photo: A West Coast lady butterfly, which has seen its numbers drop by 80% in two decades. (Renee Las Vegas/Wikimedia Commons, CC BY).

Sign up for The Invading Sea newsletter by visiting here. To support The Invading Sea, click here to make a donation. If you are interested in submitting an opinion piece to The Invading Sea, email Editor Nathan Crabbe at ncrabbe@fau.edu. 

Tags: butterfliesdroughtEndangered Species ActinsecticidesKarner bluemonarch butterflypollinatorsWest Coast ladywildflowers
Previous Post

Art, action unite at Florida Climate Correction Conference

Next Post

Floridians should fight latest utility rate hike 

Next Post
A Florida Power and Light electric substation (iStock image)

Floridians should fight latest utility rate hike 

Twitter Facebook Instagram Youtube

About this website

The Invading Sea is a nonpartisan source for news, commentary and educational content about climate change and other environmental issues affecting Florida. The site is managed by Florida Atlantic University’s Center for Environmental Studies in the Charles E. Schmidt College of Science.

 

 

Sign up for The Invading Sea newsletter

Sign up to receive the latest climate change news and commentary in your email inbox by visiting here.

Donate to The Invading Sea

We are seeking continuing support for the website and its staff. Click here to learn more and donate.

Calendar of past posts

March 2025
S M T W T F S
 1
2345678
9101112131415
16171819202122
23242526272829
3031  
« Feb   Apr »

© 2022 The Invading Sea

No Result
View All Result
  • News
  • Commentary
  • Multimedia
  • Public opinion
  • About

© 2022 The Invading Sea

Welcome Back!

Login to your account below

Forgotten Password?

Retrieve your password

Please enter your username or email address to reset your password.

Log In