Leaf Mines

Autumn is a good time to look for leaf mines. A number of groups of insect have larval stages that feed in leaves, leaving a characteristic trail. As many leaf miners are specific to one or few species of plant, it is often possible to identify the insect from the pattern of the mine and the species of plant. These websites are useful guides to identifying leaf mines.

http://www.leafmines.co.uk/index.htm

http://www.ukflymines.co.uk/index.php

Amongst the flies, the family Agromyzidae is the main group that make leaf  mines. Some hoverflies 
also have leaf mining larvae. Notably Cheilosia caerulescens is a miner of house leeks Sempervivum. 
It has not yet been recorded in Northants but has been found in Bedfordshire. Look out for mined 
leaves of house leeks. Visits to garden centres may be productive as it is thought that the fly entered
Britain in imported plants.

When the weather is not suitable for finding adult flies, looking at leaf mines is a good way of 
recording species. Last week I found Agromyza filipenduli on meadowsweet, Liriomyza eupatorii
and Phytomyza eupatorii on hemp agrimony and Agromyza alnivora on alder leaves at Yardley
Chase.

Phytomyza eupatorii leaf mine on Hemp Agrimony

 Agromyza alnivora leaf mine on Alder

Agromyza alnivora leaf mine on Alder. The larva is visible as a small dark object at the top of the mine (not
the larger brown blotch)