Zoologist hunts Moraine for undocumented species of caterpillar
MUDDY CREEK TWP — The hunt was on Saturday morning, April 25, as a group of five people scoured the Pleasant Valley Trail of Moraine State Park for horse balm plants, also known as richweed.
Pete Woods, invertebrate zoologist with the Western Pennsylvania Conservancy, found evidence last summer of a creature feeding in the shoots of the plant — he noticed leaf mines in stoneroot leaves. He surmised that the culprit was a species of caterpillar — one that has not been documented before — and explained that it could have gone undocumented because it and its fully-matured form resemble another species.
Woods brought more people into the search Saturday as part of the City Nature Challenge, an international effort for people to find and document plants and wildlife. He explained to the small group what they should search for: small twig-like plants topped by jagged leaves that grow perpendicular to one another. But finding an example of the caterpillar would require the seekers to feel the stem of the plant for lumps, which would indicate that a caterpillar was feasting on it from the inside.
“If we found this particular caterpillar in this particular host plant we would probably be able to recognize it,” Woods said. “The key to finding mature caterpillars is looking for them in the spring when they are burrowing up into the shoots. It should be possible to find them.
“It's a small caterpillar within a fleshy shoot, but I'm hoping to see a little wrinkling.”
It was a difficult search on the rainy day as the five people crouched over patches of the richweed feeling for caterpillar bumps. There were a few false alarms as people called Woods over to look at a plant that ended up just having a bent stem.
Raelynn Harrison, environmental education specialist with the Western Pennsylvania Conservancy, invited people who took her Master Naturalist course in the fall to join in the search. Even during the search, the people there enjoyed pointing out interesting plants to one another, including fungal growths on trees and the occasional invasive species that they said should be taken out of the park.
But Woods ended up taking a few samples of the plant with him for further studying. He said if he doesn’t find the caterpillar in his samplings from Saturday, he will continue the search later.
It would take some effort to get the mystery species documented even if the samples Woods took do turn up with live examples of the animal.
“When I actually find it, I want to rear it to adulthood which is necessary for defining a species,” Woods said. “At some point the caterpillars would exit the host plant and pupate, it would metamorphosize into a moth.”
Started in 2016 as a competition between Los Angeles and San Francisco, the City Nature Challenge has grown into an international event, motivating people around the world to find and document wildlife in their own cities. The challenge is an annual four-day global bioblitz at the end of April, according to City Nature Challenge’s website.
Even though the search didn’t bring home any concrete examples of a new species, the attendees said they enjoyed the outdoor outing. Woods also said that it’s his job to search for species that may be rare, because they could need to be conserved once discovered.
“Part of my duty is documenting everything that I can insect-wise that's in a place. See if I can find anything rare, anything that would be a conservation target,” Woods said. “If we did find something rare, we would want to bring it to the attention of the park managers.”
