Saturday 19 December 2020

Nemapogon granella and friends

Back in March, I posted here about finding Nemapogon cloacella indoors. I found a total of four moths in March and another in May. After a gap, I found some similar-looking moths in the kitchen on several occasions in September, including this mating pair which I put down as N. cloacella without much thought. I also found more in November.

Nemapogon sp.,
Newton Longville 11 September 2020

I've gradually learned to pay more attention to what is written in the field guides and in other sources, and that some species can appear very similar to other species. My suspicions about the IDs of what I was finding in the kitchen were already beginning in September and I started to wonder if there was a chance that at least some of them (including the pair above) might be Nemapogon granella - but by the time I got sufficient doubts I no longer had the moths. When another couple of moths appeared in November, I sent them to Peter Hall to have their bits examined and they both came back as N. granella. This month, I've found a couple more in the kitchen and I'm fairly confident that they are also N. granella.

Initially, I believed that I'd only started to see N. granella in September. This made me wonder whether they were accidental imports: in the summer we managed to spend 3½ weeks in France (before quarantine was introduced: those were the days!) and returned with a large amount of vegetables from a local market gardener, including plenty of drier material such as shallots. However, in going back through some of the photographs I had taken in March, I'm no longer so sure that they were all N. cloacella. So perhaps the N. granella didn't come back from France in my car.

At least one of the moths from March may be N. granella and the other looks like a candidate for N. varietella (see the white hair on the head). As I didn't pay enough attention at the time to the possibility that they could be one of the rarer species and didn't send them for gen. det., I'll never know for sure, so where I have doubts, I'll change my records from Nemapogon cloacella to Nemapogon sp.


Nemapogon spp.
Newton Longville, 15th & 20th March 2020

As I've been looking into this, I have found at least three different descriptions of visible differences between N. cloacella and N. granella (and the other three similar species), but none of them seem to be very reliable when I look at photographs - including the photographs on the same websites as the descriptions of how to tell the difference! So gen. det. seems the only reliable method.

I have also noticed that N. granella has very few records in most counties. I wonder if it's under-recorded if other people are doing as I did earlier this year and defaulting to an assumption that they are finding the much more common N. cloacella

Tim Arnold
Newton Longville, Bucks

1 comment:

  1. Hi Tim,

    I suspect you are correct about Nemapogon granella being under-recorded and there are other look-alikes apart from cloacella which need time and effort to separate too (dissection often being the only safe way to do it). In Bucks your records for granella are only the third site for it, the others being from the Burnham Beeches RIS trap and from Northmoor Hill Wood near Denham, co-incidentally the site where Robin Knill-Jones was trapping the other day. At the latter location the species was reared from larvae found in bracket fungus and I suspect this will be the food-plant for those at Burnham Beeches too. I doubt that you've got fungus inside your kitchen (!) so dried food products are a likely source.

    There are VC24 records for koenigi (several), ruricolella (several) & variatella (1, again reared from larva in fungus) as well as cloacella (lots). There are also quite a lot of records for clematella but at least that one is quite distinctive.

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