Something NEW!

A few weeks back I was caterpillar-hunting along field edges and roadsides associated with a local airport in Swanzey, New Hampshire. Logan Dieck, a visiting high school senior from California who has been volunteering at The Caterpillar Lab, was with me, and I was hoping to show him how to locate some long-standing favorite caterpillars... the decorator emerald on daisy fleabane; silver spotted skipper on groundnut; maybe a Cucullia on goldenrod.

 

As my eyes wandered to the usual assortment of “high value” caterpillaring plants, Logan’s eyes searched more broadly and fell across some plants I had long ago written off as uninteresting, rarely seeming produce caterpillars of any kind. It’s the trap of a seasoned caterpillar-hunter, or naturalist of any kind; we build up expectations and assumptions based on past experiences and may fail to examine certain plants, habitats, possibilities as well as we should because they have proven unproductive in the past.

 

Well... Logan is an astute young naturalist, extremely knowledgeable and with an eye for detail that we may all once remember having in youth but can’t boast of to the same degree today… and he very casually picked up a small, red-brown caterpillar with contrasting white chevrons from a piece of dead and dried pinweed. Pinweed, Lechea, is an assumed “filler” plant that very few insects are known to be associated with at all!

 

When Logan held up his find, I lost my calm pretty quickly. Sputtering, I took it in hand and tripped over my words as I tried to explain in a jumble that he had just picked up something NEW. Something that no one had ever seen before. Something that didn’t fit any of the usual suspects. Something pretty freaking fantastic! And on a plant that nothing is supposed to eat! I think Logan got the idea… and hopefully I wasn’t the only one feeling a surge of adrenaline in that moment, the thrill of discovery.

 

Subsequent searches of Lechea across the sandier portions of the airport turned up not just a few of these new and mysterious caterpillars, but dozens of them across three different species of pinweed! Later on, a lepidopterist friend in VT, JoAnne Russo, visited a power line cut with pinweed and found one of her own! The discovery made and the host plant acknowledged, now these stunning little caterpillars, whatever they end up being, are on the radar!

 

After further research and discussions with other experts, we have an idea forming as to what these lovely, unlikely caterpillars could be - and the options are all quite exciting!

 

The most likely fit: Derrima stellata, the pink star moth, is an uncommon and local Heliothine sun moth with a lot of flare. The adult is bright pink and yellow with a series of sharp white mercury-like spots. It is similar in color to moths like the rosy maple moth, primrose flower moth, and pink prominent, but it has its own unique take on the pink and yellow outfit. As such a distinctive moth, it is surprising that its life history has remained a mystery. No pink-star moth caterpillars have ever been found or concrete host associations made. Until perhaps now! Given time of year, habitat, size, and relative lack of alternatives, Logan Dieck’s chance find on pinweed may have finally solved the long-standing mystery!

 

Other possibilities: The Schinia flower moths are close relatives of the pink star moth and many have life histories that remain undescribed. In New England only one seems to fit with our find, Schinia spinosae, but its flight season tends to be later into the fall than Derrima so we don’t feel like it is as likely to be our creature. If not Schinia spinosae, there is also a chance that our caterpillars could represent an undescribed species all together, something that has an adult moth stage that mirrors closely a known species, but whose caterpillar - our creature on pinweed - has diverged in habit and form significantly. Finally, there are a few very mysterious Heliothine sun moths that are very rare and local that we know almost nothing about. A good example would be Melaporphyria immortua, but again, this seems like a much less likely possibility than Derrima stellata!

 

So now Logan is back in California, and The Caterpillar Lab chugs along with its summertime programs and outreach, while a few containers of these mystery caterpillars eat away at piles of harvested pinweed and start to finish up and pupate in small vials of soil. It likely won't be until next year that we see the resulting moth first hand, but in the meantime we have some more sleuthing to do. Right now caterpillar-crazed people like us are looking on pinweed up and down the eastern seaboard hoping to confirm more of these caterpillars in locations where the pink star moth is known to occur as an adult. Meanwhile, a sample of a few caterpillars has been collected by David Wagner in CT to send off to get genetically identified so that we can both preserve a genetic imprint of this mystery caterpillar and perhaps find out a little sooner exactly what we found!

 

We hope to eventually publish a short paper describing this new caterpillar, especially if it turns out to be Derrima stellata or any of the other short-list of possibilities. We know there are already people out there looking for more and would love to hear if the pinweed in your neck of the woods ends up hosting this beautiful species!