Browntail Moth Caterpillar Research in Maine
By Jason Aylmer
Browntail moths pose a significant problem to Mainers with larger infestations in recent years, leading to efforts by local authorities and communities to control their population. For the uninitiated, the caterpillars of the browntail moth (Euproctis chrysorrhoea) have tiny toxic hairs that can cause skin irritation upon contact and, if inhaled, can lead to respiratory issues such as difficulty breathing and irritation of the throat and lungs. The hairs can also cause allergic reactions in some people, ranging from mild itching to severe rashes and blistering.
University of Maine professor Dr. Angela Mech and PhD candidate Devin Rowe are researching how to address this problem in ways that cause minimal harm to the environment while still providing maximum efficacy. Below, we discuss how they got involved in browntail moth caterpillar research and what promising solutions are emerging from their research.
How did you get started in the field of browntail moth caterpillar research?
Dr. Angela Mech: I was hired in January 2020, in the middle of the current browntail moth Caterpillar outbreak, and it was insinuated, during the hiring process, that; “Wow, we can’t wait to see what you’re going to do about this!” I knew what I was walking into, although perhaps not quite to the extent of how severe the rash could be, but was very familiar with this specific species. I knew that it was a big enough issue that I hit the ground running and had been applying for grants before I even officially started, trying to make sure that when I came up here, I could begin right away.
Devin Rowe: The browntail moth came to me. Dr. Mech’s research is all about forest entomology and my background is in medical entomology (I did my master’s on mosquitoes down at the University of Tennessee, Knoxville). I was originally applying for a different opportunity in Dr. Mech’s lab, which I did not get, but then she mentioned that she had something better: a fully funded PhD to study the browntail moth.
Biologists love to use the word “charismatic” to describe animals that people find charming — like a monarch butterfly. The browntail moth is charismatic for how bad it is. When someone hears that there’s this caterpillar that can release hairs that cause a poison ivy like rash, it’s an interesting story. So once I learned a bit about the insect, I was like: “Sure, I’ll do it! I’ll be fine getting rashes.”
Dr. Mech: Our specialties are such a great combination, because this is a forest health pest but it’s also a public health pest. In forest entomology, we don’t normally deal with public health but browntail is just one of those weird insects that checks off all these things that I wasn’t trained for, just as much as medical entomologists aren’t trained in forest ecology. It was an interesting scenario: I had posted for the PhD student, sending it through listservs and posting it on websites, and I didn’t get a single person to apply. So when Devin applied to this other position, I was like: “He’s got everything that would really line up well for this PhD. I wonder if he might be interested?” I don’t know if people just Googled browntail and decided “Nope, not applying!”
What are some of the promising solutions to browntail moth infestation that are emerging from your research?
Rowe: We will have an even better idea after this summer, but part of the main core of my research, and that of our lab, is trying to see if pheromones can be the answer. Essentially, we are looking at using the females’ mating pheromones to disorient the male, which will interrupt the mating cycle and result in fewer itchy caterpillars the year after. This has been successfully done with other types of similar moths, so promising results would be a great way to control the situation. It is a way to manage the moth that is not going to target other insects. If you use pesticides, most will harm other types of insects but mating disruption is specifically keyed to whatever it is trying to target.
Dr. Mech: We’re really hoping that this has some positive results. Our pilot studies have been looking promising. Also, Devin and another grad student did a survey and asked Mainers if they would be interested in something like pheromone disruption, where you would basically inundate the air so it would all smell, to male moths, like a big female moth. It would require everyone in that particular area to be onboard and we were curious what people thought about this. Are we wasting our research time looking at something no one would approve of or want done. We were excited: we saw very high acceptance – 80% – when we explained the idea, which exceeded our expectations.
What do you love about your research?
Rowe: browntail moth research is fascinating. It is an understudied species and most American studies were done in the early 1900’s during the initial New England Outbreak. Even in browntail moth’s native range (mainland Europe), there are a few papers every few years, but few and far between. Besides reading journals, the current research for this insect is kind of like an archaeology dig trying to find these super old papers. Dealing with an insect that is not studied a lot is fun. For example: I have used AI-assisted translations for verifying historical browntail moth documents. I was able to cross-verify a 1792 English paper about a browntail moth outbreak in London, which referenced a 1732 browntail moth outbreak in France. I was able to directly confirm what the 1792 author was saying once I was able to look into the multiple translations I had run for the 1732’s French paper. A lot of detective work!
Dr. Mech: I will add to that exactly what Devin said: this is a system that is very understudied. So it is very exciting that everything we are answering hasn’t been answered yet. There’s so many different avenues, which, at the same time, can be exciting and stressful because there’s almost too many things that we don’t know. So, the good and the bad is that we have to test and test and test many different things, and sometimes we get overambitious with the numbers of tests we want to run because we have so many open questions.
If you’d like to read more about Dr. Mech and Devin’s research, here is their latest research update.
For more information on what you can do to help mitigate the effects of browntail moth caterpillars where you live, visit the UMaine Extension’s Browntail Moth page.