Species of the Month October 2021

Beech leaf-miners: Stigmella tityrella and Stigmella hemargyrella

 

Leaf mines are marks on leaves left behind by the feeding signs of larvae of species including moths, flies and beetles. On Beech leaves there are two common leaf mining moths: Stigmella tityrella and Stigmella  hemargyrella. Both create "gallery mines" - i.e. a narrow channel meandering across the leaf surface as shown in the images above.

Although these mines are similar, you can tell the two species apart by a couple of markers:

Location of the egg - this is at the start of the mine, at its narrowest point. S. tityrella always lays next to the mid rib of the leaf, whilst S. hemargyrella lays the egg anywhere on the leaf surface.

Pattern of the mine: S. tityrella will be contained within one section, usually displaying a distinctive zigzag pattern (shown in the upper photo), while S. hemargyrella will travel across the whole leaf surface (shown in the lower photo).

If you are unsure which species you have found, you can send a photo of the mine to info@sewbrec.org.uk to double check. You can find more images and information from British Leafminers.

Of course the first step to finding these species is to identify the Beech tree host; please take a look at Tree Guide UK if you are unsure how to do this.

These leaf-miners are likely to be present on Beech throughout south east Wales, but we only hold 123 records of S. hemargyrella (Welsh distribution map) and 210 records of S. tityrella (Welsh distribution map) at SEWBReC.

If you spot either Beech leaf-miner during October (or at any other time of year), please send us the record, ideally via SEWBReCORD or the LERC Wales App. Instructions on how to submit records are available here.