Methods
Mine of Phytomyza glechomae on Glechoma hederacea.
Collecting mines
Miners are recorded throughout the British Isles. Mines may be sought wherever their host plant or plants grow. Some mines are very obvious and will be easily discovered e.g. those of Phytomyza ilicis on Holly (Ilex) and Pegomya species on Docks and Sorrels (Rumex) and Knotgrasses (Polygonum), others are difficult to find without a thorough and extensive search e.g. those on grasses and sedges.
On discovering a leaf mine, you should endeavour to identify its host plant in situ, preferably by reference to a field guide. British wild flowers may be identified using either one of the numerous published floras such as Francis Rose's 'The Wild Flower Key British Isles-N.W.Europe with keys to plants not in flower' first published by Frederick Warne in 1981 and reissued in 1991 or online at. It is usually easier to identify flowering plants when in flower. Unfortunately not all mines occur when the host plant is in flower, so it may be necessary to visit the site again to re-examine a host plant.
If possible take a photograph or digital image of the host plant in situ. Where it legal to do so, remove mined leaves and stems avoiding unnecessary damage to the host plant. Transfer the mined leaves and stems to a polythene bag in which you have placed a sheet of white paper to absorb excessive moisture. If you have been unable to identify the host plant, collect a flowering stem and some undamaged leaves and place them in the polythene bag with the mined stems or leaves for later examination. If you have been able to identify the host plant make a note of the identity. Write collection data, such as the name of the host plant, location, date of collection, using a pencil on a slip of paper and place this inside the bag. Keep the bagged mines out of sunlight to avoid overheating.