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Oak Marble Gall Andy

Oak Marble Gall

(Andricus kollari)

Also known as 'Oak Nut' These mature Oak Galls were caused by a tiny wasp which laid her eggs inside a leaf bud, the larvae secrete chemicals which have a reaction inside the leaf. The gall which is really a mutated leaf then grows around the wasp larvae.  The Marble Gall is green and filled with a spongy mass of plant tissue from which the single larvae feed.  As the gall matures it turns hard,  brown and feels like wood, other insects can be found inside a gall including parasites which feed on the Gall larvae.

Life History

The Gall wasps have a very interesting life history, in May and June a mated female lays her eggs into the buds of our native oaks. Which produces the familiar gall shown in my picture above. Inside develops a single larvae which are a female which emerges in September. When the infertile female emerges it lays its eggs into the buds of the Turkey oak, these galls grow through the winter months. The wasp which emerges in the spring is a sexual generation consisting of males and females which then go looking for our common native oak trees and so the fascinating cycle continues.

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