Micro-moth field tips: Prays fraxinella
(22.002). Early May is the best time to look for the feeding signs of this species, as small saplings of ash may contain noticeably wilted shoots. If one looks carefully at these, frass may be seen emanating from the base of the shoot. If you break off the wilted shoot, there is a hole leading into the main twig. The larva can be seen within this, as in the second photo below (although check the larva isn't in the broken-off shoot before you've disposed of it!). Pupation occurs within a netted cocoon, either within the feeding place or elsewhere on the tree. The larva, will feed on fresh ash shoots in captivity.
There is a small uniformly dark form and DNA evidence suggests it is a seperate species Prays ruficeps
(22.003). I have no knowledge of the feeding signs of the latter.
Thanks to Ben Smart for photos and information.
For ruficeps, the larvae feed in the bark of Ash also. This separation is causing a few headaches. I've been working with 2 others finding reliable differences via dissections, and so far we have only one slight difference for males. There is the dark form of fraxinella also, but the moth is larger and you can usually still see a semblance of wing pattern under the black. Ruficeps is smaller and as the name suggests, has an orange head and is completely dark over the wings. I had one site 3 years ago where ruficeps was abundant and for a while, it was easy to separate. I haven't seen it since! If in doubt, keep any adults. Being a pessimist, I'm assuming Ash dieback will solve the problem soon anyway.ReplyDelete
Thanks for that Peter, I should have been a little clearer re the darker form just in case anyone decides to rear any larvae they find.ReplyDelete
I have been looking for a photo of a dark fraxinella, I know I had one somewhere as I used to get them from next door's ash tree in Lancs.