Insect mines - methods
Rearing
Rearing
On return to your base, carefully remove the mined leaves and/or stems you have collected from the polythene bag and photograph or digitally image them on a white background and, if possible, on a back-lit sheet of glass. Transmitted light passing through the mine will often reveal detail not apparent using reflected light. Document your images carefully.
Any unoccupied mines, once photographed or digitally imaged, should be pressed using a plant press. Remember to document them. Return any occupied mines to the polythene bag, seal it and keep it out of the sunlight in a cool place to await the emergence of the miners (adults or larvae) or any parasitoids. If the mines are incomplete when collected you may wish to take further photographs of the mines as they develop.
Mines of Phytomyza spondylii or pastinacae (Agromyzidae) on Heracleum spondylium (Apiaceae) taken one week apart.
Species pupating within the leaf, e.g. Chromatomyia species, will usually emerge within a couple of weeks. The pupa or puparium of species which pupate externally can be carefully transferred to a small plastic box lined with white paper using a fine moistened paint brush. The white paper will enable you to observe the pupa or puparium more easily. Some miners emerge from the pupa or puparium within a week or two, but others with only a single generation per year or towards the end of the year will overwinter. The later are usually very difficult to rear out!
Leaves and stems with empty mines, if not decomposing, should be pressed and retained.