Holly Leaf Miner
Holly Leaf Miner
A Holly Leaf Miner is a species of small fly, belonging to a group of flies which are characterised by their larval-mining behaviour. Larvae of the holly leaf miner burrow within the leaf tissue of holly plants. They create distinctive tunnels as they eat through the internal plant material, causing patches of discolouration to occur.
The larvae of this fly will leave unattractive mines across the foliage of infested plants where it's been feeding.
Scientists are able to determine what predates holly leaf miners from the emergence holes in holly leaves.
With leaf-mining insects, identification usually is best achieved from the species of the plant infested and characteristics of the mines. With this leaf miner, the mines will be evident on the leaves of holly plants. Look out for raised areas on holly leaves. Mines are distinctively yellow and white, however, can have areas of brown patching within the blotches. Blotches do tend to cross the central leaf vein. Holly leaves are unique to other plants which are mined by leaf-mining insects. When larvae leave the leaf, they will make a tear in the mine. Scientists use these tears to identify if larvae left voluntarily, or if they were eaten by something else. We now know that blue tits and parasitic wasps heavily predate these flies.
This leaf-mining fly can cause some defoliation as a result of their feeding. You should not be alarmed by leaf falls in summer; this is normal for holly. Yellow, white and sometimes brown-purple patches may be seen on the surfaces of holly leaves. Holly plants can tolerate these miners.
Europe and Northern America.
It's not advised to treat plants infested by these insects because holly can tolerate infestations. It's now known that these flies are readily hunted by blue tits and parasitic wasps.
Insecticides are unlikely to work because of the thick and glossy leaf texture, making it difficult for chemicals to penetrate larvae in the leaf mines.
Blue tits and parasitic wasps readily hunt the larvae of this insect.