Sunday, May 17, 2020
Things on hornbeam leaves
I seem to have been doing well with hornbeam leaves this year, especially as they do not normally seem to produce anything very exciting. My first discovery was the tiny galls of the mite Aceria tenellus in the axils of veins in several leaves of the hornbeam cordon in my Square Metre, as well as on the edge of Killingan Wood up the lane. There are only a few records of this species from Sussex and I expect it has been overlooked rather than being generally scarce.
My next discovery was of quite a few empty mines of the small purple hazel moth Paracrania chrysolepidella (it also feeds on hazel), an attractive, Nationally Notable class B, early flying micro.
While examining these I noticed a strange corkscrew like gall on a leaf edge (see below) which turned out to be that of another mite, Aceria macrotrichus. According to the National Biodiversity Network (NBN) there is only one British record of this (from the Midlands). There were no Sussex records in the databases of the Sussex Biodiversity Record Centre. As well as the corkscrew-like structure there are vermiform swellings along the veins in the underside of the leaf and slits on the upperside from which the mites can leave
The next day I was looking to see if there were any more of these galls. There were not, but I found the considerable mass of eggs (see below) that some insect had laid on the underside of a hornbeam leaf. After arrival at home they started to hatch into tiny caterpillars, so I have put them on the hornbeam cordon down the garden in my Square Metre project.