Saturday, 7 September 2019

Searching for Miners - Wern Claypits Nature Reserve Saturday 31 August

This was a training session that opened up a whole new world to some of us attending this daytime event. Douglas Boyes led the event and provided us with copies of: “The Identification of Leaf-mining Lepidoptera” (available on the website ) which provides a key to leaf mines by food plant, so if you can identify plants and trees you stand a chance of finding the relevant leaf miner. Armed with the knowledge that there is only one leaf mine that feeds on Meadowsweet, I proceeded to present countless mines to Douglas only to learn the hard way that Lepidoptera are not the only miners!  Apparently flies do it too.  And the mines look pretty convincing until you get your eye in with the frass (their poo).  Yes, we learnt a whole new vocabulary too.
Sue, Tim, Douglas and Peter considering the options

Once Douglas had given us the basics, off we all went searching each tree and plant around the nature reserve for what we hoped would be Lepidoptera.  The weather was fairly kind to us, and the site excellent.  

The leaf miners fall into a number of families with different mining characteristics, so some of them tunnel in the leaf causing gallery mines and occasionally leading to blotches (the Nepticulidae) and some make folds or blisters or blotches, or even cones (Gracillariidae). Some mines are found in the leaves, but some are found in the seeds – for example Field Maple. 

We targeted certain “easier” trees: Field Maple, Alder, Ash,  Blackthorn & Hazel, and with Douglas’ help we were able to identify a number of species. For example on Hazel we found all three gracillariid species – one which causes a blister on top of the leaf (Phyllonorycter coryli), one where the larva feeds in a rolled leaf edge (Parornix devoniella) and one a long mine with a strong central fold (Phyllonorycter nicellii). 

Phyllonorycter rajella on Alder
Some species are not identifiable from the mine alone, and you need the larva or to rear to be certain. And some trees are more challenging – for example Oak, which has many species living on it.  This didn’t stop Gavin searching every Oak tree!

We didn’t spot many flying moths – just a Nettle-tap ably netted by Gavin and a Brown China Mark seen by the canal and captured by the swift camera of Sue.  We also found the larva of a Mother of Pearl wrapped up in a nettle leaf and a Yellow-tail larva in an Oak tree.  
Among the highlights of the day were the breeding record of Caloptilia falconipella, found on Alder.

Altogether we totalled 32 records – mostly leaf miners – so it just shows that it is worth taking time to look at the little things – and it is something you can do all year round and really add to the records.  There is a book: “Micro-moth Field Tips” by Ben Smart, which is a guide to finding the early stages of micro moths (not just miners) by every month of the year.  Worth a look.  It means we can keep moth-ing right through the year. For full species list click here.

 Many thanks to Douglas for a really interesting session (and for making sure I got this report right!), and to Sue for taking photos and keeping the list of records on the day, and to everyone that turned up (even Peter found us eventually!).

Brown China Mark
Caloptilia Stigmatella on Willow

Caloptilia semifascia - the larva feeds in a cone
 formed from the leaf of a Field Maple.