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Knopper Gall of Acorns



P_acornglwsp

Knopper Gall of Acorns

Usually appear in

Summer


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Caused By:-     The Wasp Andricus quercuscalicis

Description

The Acorn Gall wasp(Andricus quercuscalicis) causes Knopper Galls of Oak(Quercus) acorns. The wasp lays its egg on a developing acorn in early Summer. When the egg hatches the grub secretes chemicals which causes the acorn to develop into a gall. The grub pupates inside the gall and emerges in the following year. They have a two generation cycle and are usually found on trees in the same area as Oaks. The first generation adult wasps, all female, leave the galls in early spring and lay their eggs in oak buds. A sexual generation of male and female wasps hatch and mate, with the female returning to lay eggs on the English Oak. This wasp has only been recorded in Britain since 1962. The new galls are bright green at first, darkening with age. They then drop from the tree. Picture by Haruta Ovidiu, University of Oradea, Bugwood.org
See also these other Galls ACER GALL MITES, ACORN GALL MITES, AZELAE GALL, BEECH GALL MIDGE, BLACKCURRANT GALL MIDGE, BROOM GALL MIDGE, CAMELLIA GALL, CROWN GALL, EUONOMUS GALL, FELT GALL MITES, FORSYTHIA GALL, GALLS, GALL WASP, GLEDITSIA POD GALL MIDGE, HEMEROCALLIS GALL MIDGE, HAWTHORN BUTTON TOP GALL MIDGE, LEAFY GALL, LIME NAIL GALL MITE, OAK GALL WASP, PEAR LEAF BLISTER MITE, PINAPPLE GALL ALDELGID, PLUM GALL MIDGE, ROBINS PINCUSHION, TURNIP GALL WEEVIL, VINE ERINOSE GALL MITE, VIOLET GALL MIDGE, WILLOW BEAN GALL SAWFLY.


Control

Unless the infection is great spraying is not necessary as most Oaks can cope with some predation. In any case the trees are too large for spraying.


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