Holly Leaf-miner

Leaf mines are mainly caused by species of Lepidoptera (moths), Diptera (flies), Hymenoptera (sawflies, bees, wasps & ants), and a few Coleoptera (beetles), whose larvae feed within the leaves of plants. As the larvae feed and grow, they move throughout the leaves, creating mines. The mines created by these species are often very distinctive and, coupled with the fact that leaf-mining species tend to be restricted to a certain range of host plants, it is often possible to identify mines to an individual species.

The first step in working out a miner's identity is correctly identifying the host plant. Doing this normally narrows down the possibilities quite a bit and then you can identify which type of insect (order) the miner is from:

• Lepidoptera normally make full depth galleries or blotches with single lines of frass (droppings).
• Diptera mines are either lower- or upper-surface (or a mix of both), their larvae are maggots and they characteristically make twin trails of frass.
• Hymenoptera mines are blotches rather than galleries and characteristically have extensive amounts of dark frass (compared to diptera mines). The larvae of Hymenoptera also have visible legs.

Phytomyza ilicis is a species of fly (diptera) whose larvae mine the leaves of Holly (Ilex aquifolium). P. ilicis is incredibly common and is the only species to mine Holly in Britain, making it very easy to spot and identify! It is abundant on the UEA campus, with P. ilicis mines visible on just about every Holly bush you come across.

Phytomyza ilicis leaf mine on holly