When you trap one of the rarest moths in the county, with just a handful of records over the last few years, you consider yourself lucky. When you do it again 10 days later, well …!
With the threat of rain overnight, I put the trap under the sun umbrella on our garden table and the underside of the canopy was plastered in moths come the morning. Having spent 20 mins recording these, and then opening up one side of the trap and dealing with the plethora of moths inside, I had already been at it for 45 mins before I even saw this moth …
There, for the second time in 10 days, was a Bedstraw Hawkmoth, an insect that many moth-ers may never seen … and I’d found two in as many weeks. What a cracking moth!
So, just how lucky am I?
Well, the answer to that depends on what the most likely scenario is. One obvious possibility is that I’m only as lucky as the first time because this was the same moth, re-trapped having lingered near my garden. With this in mind I looked back carefully at the photos from the 3rd August and they suggest that this is not the case.
As you can see, the extent of the black markings on the hindwings is different, with a distinct bulge on the new moth not present on the old one. Whilst moths might lose colouring over ten days as the scales wear away, it couldn’t have gained this extra black marking. These look like two different specimens therefore.
So, the second possibility is that I’ve simply managed to trap two immigrants … but with just a very few records for the UK every year, and very few of these in Devon, the odds that these were two immigrant moths and had both stumbled on my garden are surely negligible.
But there is a third possibility which is that far from coming from miles away, these moths are the progeny of a local breeding pair, or pairs, and have therefore emerged nearby. This seems the likeliest – and most exciting – probability … still immensely lucky that reproduction happened locally but, given that it did, then statistically fairly likely that I then caught two of them. It would also explain why they look so pristine …
Perhaps what we are seeing here is the product of our increasingly mild winters. As I understand it, Bedstraw Hawkmoths spend the winter underground as a pupa and the caterpillars then are active from July to September. However, the pupal stage ‘does not usually survive’ our wet winters (Waring, Townsend and Lewington, 2012, p. 167); though over the last 50 years or more there have been temporary resident sites in different parts of the UK, especially in the SE. It looks like at least one pair of pupae have managed to do so here, even though last winter was a wet one. Either way, a fabulous moth to have nearby and coming to the trap. Let’s hope that the population lingers and, perhaps, even manages to take hold permanently.
As if that wasn’t enough, Matt then called me to say he had trapped Dark Crimson Underwing in his Exmouth garden just a few miles away!
DCU is pretty much as rare as the Hawkmoth, with just 38 British records in the Atlas (Randle et al, 2020) since 2000 and only one site showing in Devon. To see this, as well as the Hawkmoth, made for a fabulous day, with the promise of more to come given the hot and humid weather forecast.