purple bunch of beech gall midge mikiola fagi, cecidomyia fagi

plant galls agricultural disease gall mites spot infection hama diseased warts linden mite parasitic botanical ball pustule aceria phloeocoptes blister leaf bump botany bad illness pathogen tungau puru leaves garden benjolan agriculture damage eriophyid parasite eriophyidae infected insect eggs green environment tree forest mikiola fagi sylvatica midge fagus beech bunch twig purple cecidomyia caused cecidomyiidae fly