British Butterfly Thrives on Climate Change

Climate change is reviving   a once rare British butterfly, according to a new article in the journal Science.   The brown argus butterfly was once scarce, but has doubled the size of its range in the last 20 years.   The study, authored by biologists at the University of York, indicates that at warmer temperatures brown argus butterflies are able to feed on more common plant species, allowing them to expand into new territory.

Brown argus caterpillars normally feed on the rockrose plant, but they occasionally use plants in the geranium family during warm summers. The rockrose usually lives on sunny, south facing slopes and brown argus caterpillars depended on these warm microclimates for survival. However, for the last 20 years summer temperatures have been on the rise and the brown argus has been shifting it’s egg laying towards geraniums.

During cold summers, the brown argus butterfly uses the rockrose plant (left) but climate warming has allowed it to thrive on the wild geranium (right)

To test whether climate caused the shift in food choice, lead author Rachel Pateman and her colleagues used data collected from 200 sampling sites in southern England.  Butterfly sightings at the sampling locations were reported by volunteer naturalists, and some sites  been monitored since the 1900s.   Each sampling location had only rockrose or only geranium growing nearby.  The researchers used butterfly counts from the volunteer records and matched it to historical temperature data. They found that the butterfly populations grew faster at geranium-only sites during warm periods, and faster at rockrose sites in cool years.

The scientists also looked at  changes in brown argus populations in the last 20 years, when temperatures have been especially warm.  They found that the brown argus had become  5.3 time more plentiful at geraniums sites, but that

The brown argus has nearly doubled the size of its range in the last 20 years. Dark red and blue are locations where it was found prior to 1990, the light blue and pink circles indicate new territory gained in the past two decades. Most gains have been in areas where geraniums are found.

rockrose areas had not changed at all. The butterfly had also expanded it’s range north by 79 kilometers in just 20 years. Co-author Chris Thomas thinks that the common geranium plant may serve as a stepping stone, allowing the brown argus to branch out into new regions without having to fly long distances.  Says Thomas “Wild Geraniums are widespread in the landscape, the butterflies can now move from one patch of host plants to next and hence move rapidly through the landscape expanding their range generation after generation.”

While climate change has been an unexpected bonus for the brown argus, it’s unlikely to be such a boon for other species.  According to Stanford biologist Terry Root (who was not involved in the study), for every species that turns out to be a climate change “winner” there are expected to be three “loser” species that suffer population declines or go extinct.

And We’re Back. Let’s Talk Peer Review

Hello fellow butterfly enthusiasts! It has been a long time since I’ve posted, but we are almost at the 1 year mark for the blog! Things have been really busy here for me. I finished all of my analysis from my experiments last summer and I have already started doing experiments this summer. Also on a personal note my grad student husband and I are expecting a baby girl by the beginning of September. We’re both really excited and luckily the pregnancy hasn’t slowed me down too much. Here’s a picture of me after catching Colias butterflies here in North Carolina last week.

Catching butterflies 6 months pregnant.

So when I last left you I was analyzing mountains of data. That is mostly finished and I’d love to tell you all about my results, but I can’t do that just yet. Here’s the reason why. In science when you finish an experiment you need to write it up in the form of a scientific paper and submit it to a scientific journal. This paper goes through a process called “peer review” before it becomes available to read. Peer review means that the paper is scrutinized by other scientists in your field for scientific errors and inaccuracies. Often times there are three reviewers per paper and they are looking for things like: “Was this a valid way to conduct the experiment?”, “Is this experiment repeatable or just random?”, “Is this researcher making claims that are not supported by their data?”, etc. They also check the paper for things like general readability, length, and making sure all the graphs and figures are easy enough to understand. Each reviewer can then accept the paper, accept the paper with revisions, or reject the paper. Rarely are papers accepted right away without having to make some revisions. Once each reviewer has made a decision about the paper, an editor from the scientific journal makes a final decision. If it gets rejected you can fix some of the issues that the reviews had and resubmit the paper to another journal. If it gets accepted with revisions, you get to make those revisions and then in a few months your paper gets published! It’s a long process, but a thorough one, and the it aims to make sure that there are no inaccuracies in science.


Peer review is not a perfect system, sometimes bad experiments get published, and the process itself is long and can seem drawn out, but it’s the best we have for now. It’s like fact-checking an article in the newspaper. You want to be able to trust that the news is unbiased and reporting the facts. It’s the same way in science. Politicians make policy decisions and doctors make medical decisions based on scientific research. Also as most of the science down in this country is funded by the federal government through the National Science Foundation or the National Institute of Health, scientists have a responsibility to report the facts to the taxpayers. It’s always big news when a scientist has been committing data fraud and it can be grounds to lose your PhD! However, most scientists are honest and only report true data. It makes sense when you think about why many people became scientists in the first place. They liked asking questions and discovering the answers. When scientists make up fake results they are cheating themselves out of making actual discoveries.


So that in a nutshell is peer review, and it’s one of the reasons why even though I’m SUPER excited about my results from last summer, I can’t share them with you yet. I wouldn’t want to make any scientific claims that haven’t been “fact checked” by other scientists yet. Hopefully this fall I will start writing these papers so that soon they will be published and I can talk all I want about them here on the blog! I promise my next blog post will be sooner rather than later and with more pretty butterfly pictures! Also, as a shameless plug check out this sweet Q&A article in the Raleigh News and Observer about the blog and why Sarah and I started it.

Teen Lepidopterist Decodes the Secret to Butterfly Sense of Smell

Alexandra Sourakov working in the University of Florida Butterfly house

Alexandra Sourakov has logged hours of research at the University of Florida’s butterfly house.  She used a combination of behavioral experiments and electorantennography (measurements of electrical current in butterfly antennae) to determine how butterflies find food.  Her most recent paper on foraging in Blue Morpho butterflies appears in this month’s edition of Psyche – Journal of Entomology.  Alexandra Sourakov is also about to finish her sophomore year of high school.

Sourakov began her study as part of an eighth grade science project. She used the butterflies in the University of Florida Natural History museum’s butterfly house to see whether flower-feeding and fruit-feeding butterflies responded differently to color. Sourakov used different colored landing pads baited with food to see whether butterflies preferred brightly colored surfaces to black. She found that flower- feeding butterflies were attracted to bright hues, but that fruit-feeding butterflies were indifferent to color. Presumably, flower-feeding butterflies evolved to respond to color cues because they aid in finding brightly colored flowers, while fruit-feeding butterflies usually feed on fruit that has fallen to the dark forest floor, where visual cues would be of little use.

Blue morpho butterflies sense odors with their legs and mouth parts in addition to their antennae, according to a new study by high school student,Alexandra Sourakov

After winning the science fair, Sourakov decided to scale up her research program to investigate how the fruit feeding butterflies found their food. If they weren’t using color, how did they find fruit? Partnering with USDA researcher and science fair judge Adrian Duehl, she launched a multi-faceted approach to understanding butterfly foraging. Sourakov and Duehl used gas chromatography to determine what chemicals in rotting fruit might be attractive to butterflies. They applied these chemicals as volatiles to the antennae of Blue Morpho and Owl butterflies. These two fruit-feeding species did not show any preferences for color during the experiment. With the help of electrodes, they measured the electrical output when the butterfly was exposed to different chemicals. They found that several chemicals that give bananas their distinctive odor provoked a response in the butterfly antennae. Even more interesting, they found that it wasn’t only the antennae that registered a response of the chemical, the legs and proboscis (feeding tube) also responded to the scents. The labial palpi (mouth parts on a butterfly’s head below the antennae) reacted to a different set of chemicals, indicating that butterflies may use multiple organs to detect a variety of odors.

“I was surprised by the results from the body parts because I wasn’t even sure if any of them, except the antennae, would react to the volatile chemicals,” said Alexandra Sourakov in an interview to the University of Florida News. “This was interesting because it shows a joint message may be sent to the brain from these different organs. This expands our understanding of butterflies’ sense of smell.”

The researchers hope that their work will allow them to develop new types of bait designed to target specific species of insect, while leaving other species unaffected.  You can read Alexandra’s full article here: