Back in July, I shared an assortment of moth photos I’d taken during a week on Nantucket, which happened to be National Moth Week. I included this photo of a row of flat, overlapping eggs on a woolly bulrush (Scirpus cyperinus) leaf in a marsh.
As I mentioned, this was one of three similar rows of eggs on the same leaf:
I collected the leaf in the hope of raising the larvae to learn what they were. A week later, some tiny, bright red caterpillars had hatched.
Unfortunately, they weren’t interested in eating bulrush leaves or anything else I offered them. Seeing that they were all dying, I salvaged one to include in my shipment to the Netherlands of specimens for DNA barcoding. The other day Erik van Nieukerken informed me that barcoding had identified it as Epina alleni (Crambidae), which looks like this as an adult:
Apparently nothing is known of the immature stages or host plant(s) of this moth. According to the HOSTS database, the other species in this genus, E. dichromella, has been recorded as feeding on rice in Sri Lanka. This is odd, since Wikipedia only mentions that species as occurring in the southeastern US and Cuba. I’ve grown accustomed to finding outright lies in the HOSTS database, and in glancing at the list of North American crambid moths on the Moth Photographers Group website, I found a likely explanation:
|5470||Chilo plejadellus||Rice Stalk Borer Moth|
The rice stalk borer moth (Chilo plejadellus) is listed just after the Epina species, and it does occur in Sri Lanka. My guess is that whoever added that record to the database accidentally attributed the host record to Epina dichromella because the two species were listed next to each other in whatever reference they were using. I have found clear cases of this same error before, when I had access to the book version of the HOSTS database, which cites all the sources of the host records (except, maddeningly, many of the most questionable host records are attributed to reference #492, which is missing from the bibliography).
So, as far as I can tell, no one knows what the larvae of either Epina species do, but at least now we know what their eggs (and first instars) look like. Since they are closely related to the rice stalk borer, it may be that they bore in the stems of bulrushes. If I remember correctly, this bulrush was in standing water, so it does seem like it was the intended host plant, unless the larvae are able to swim.