Sunday, June 23, 2013

Buck Moths: Reader Reaction

This is very interesting: someone who will here remain anonymous e-mailed me about last week's articles about the Buck Moth defense of stingingworms.

I've been tempted to share the whole e-mail exchange as an example of how cognitive dissonance works. The person--I think this is a good opportunity to use "person," as Marge Piercy did, as a non-gender-specific pronoun--has looked up these animals in a book and seen that some Hemileuca species are rare, possibly threatened. So person thinks they need to be protected. There may actually be some ecological niche Buck Moths fill in some places, although in Virginia, where they were locally extinct for many years, they were absolutely not missed. Person hasn't shared specific information on the value of the species. What's been debated has been the identity and toxicity of our respective pests.

What I'd like to share with readers is that this person claims that "if you touch them" (referring to Hemileuca nevadensis) "it feels like you've touched a nettle leaf." Now I have been blessed with warnings, caution, and good luck, so I've never actually touched one of what I'm guessing, based on last week's research, are Hemileuca maia. What people who've touched them have said, and what's abundantly documented on the Internet (type "Hemileuca maia" into a search engine), is that if you touch one of these things it feels as if you've been simultaneously stung by anywhere from ten to fifty bees.

Maia and nevadensis look very much alike at all stages of their lives--they merely live in different places and eat different things--and some of the scientific literature refers to "the maia-nevadensis complex" as possibly just varieties within one real species. There must be some difference between maia and nevadensis to account for their being classified as two distinct species, and it's not apparent to the eye. Is it apparent to the hand? Are nevadensis really less harmful than maia?

There's also the question of how common the things are. Like other insect populations, within my lifetime Hemileuca maia populations have expanded to meet the expanding food supply. Scott County, Virginia, exhausted its scanty supply of coal long ago and then sold off nearly all its oak trees. When I was growing up the dominant tree species was tulip poplar (which grow faster than oak or maple), the dominant tree-feeding insect was the Tiger Swallowtail butterfly, and fall foliage lasted for about a week. Now there are more oak trees on the mountain, foliage lasts longer, and we're seeing lots of new insects...unfortunately including Hemileuca maia.

"Could it be that you're seeing a different, more common caterpillar?" It could not. I didn't major in entomology at college, but I did research and write up the major differences between Malacosoma americana, Lymantria dispar, and Hemileuca maia back in the 1980s. For me these caterpillars are no easier to confuse with each other than they are with salamanders, or walnuts, or anything else that's about two inches long. They can certainly be described in words that make them sound alike, but the shapes are completely different. Nothing else really resembles the Hemileucas.

How common have they become? This year I've seen two. One year the orchard was really badly infested with six stingingworms. Trust me on this, Gentle Readers: some other species may (hypothetically) be easier to tolerate, but one of Hemileuca maia is too many. People won't pick their own fruit if they've heard that somebody else has found one!

Really large numbers are reported in New Orleans because the streets there have been lined with oak trees for a long time. We're not seeing that kind of population explosion in Virginia--yet--because oak trees are still only one of several competing species in local forests. When we get oak-dominated climax forests, then we'll have even more trouble with stingingworms. We could end up having to carry umbrellas every time we went outdoors, as people in New Orleans reportedly do, because fat, clumsy caterpillars are raining down from the oak trees. Or we could have more sense and maintain more of a variety of trees.

However, this reader reaction has motivated me to add another caterpillar species--that's not actually likely to be confused with tent caterpillars, gypsy moth larvae, or stingingworms by actual Virginia residents, but that does seem to be what the defender of nevadensis has in mind. "Black Bear" caterpillars are big, all-black relatives of Woolly Bears. They look as if they might be pests, but they're not; they eat mostly lawn weeds and, if you touch their stiff prickly hair, as I've done a few times, it feels like touching a wire brush. I'll try to get more information about them onto this site before we start seeing them in Virginia, between August and March...the "bear" caterpillars hibernate through the winter and come out for snacks on warm afternoons. "Bear" caterpillar hair can raise a mild allergy-type rash if sensitive human skin is exposed to it for a while, as can short human hair, but there is no way these animals could be confused with stingingworms either.

Meanwhile, what's the real inside story on Hemileuca nevadensis? How many Western readers have been stung by these things, and to what would youall compare the experience? I don't know, and I hope never to find out firsthand; that's what the Internet is for. If you know someone who's handled this species and can rate their sting as worse or less bad than nettle leaves', please share the information with this web site. As always, if you have trouble using the comment space below, feel free to e-mail Saloli.