Well, I didn't know this before - from a Festive message from Buglife Buglife | Help Buglife save the planet
"Ever thought about the invertebrates living on Holly?
Most famously, the Holly Blue butterfly has two generations during the year; it lays its eggs on Holly in the spring, the caterpillar feeds on flower buds, flowers and young berries. The summer generation lays its eggs on Ivy. There is a specific parasitic wasp that attacks the caterpillars, a contributing factor to the cycles of plenty and scarcity of the butterfly.
Holly leaves often have discoloured yellow and brown blotches made by the Holly Leaf-mining fly: the fly itself is far more difficult to identify.
There is even a special aphid on Holly. Few other insects have a strong relationship, though Privet Hawk moth caterpillars may occasionally be found on Holly.
"Ever thought about the invertebrates living on Holly?
Most famously, the Holly Blue butterfly has two generations during the year; it lays its eggs on Holly in the spring, the caterpillar feeds on flower buds, flowers and young berries. The summer generation lays its eggs on Ivy. There is a specific parasitic wasp that attacks the caterpillars, a contributing factor to the cycles of plenty and scarcity of the butterfly.
Holly leaves often have discoloured yellow and brown blotches made by the Holly Leaf-mining fly: the fly itself is far more difficult to identify.
There is even a special aphid on Holly. Few other insects have a strong relationship, though Privet Hawk moth caterpillars may occasionally be found on Holly.