The larva thus becomes completely enclosed in a nearly spherical mass, which projects from the twig, furnishing it with a supply of starch and other nutritive material. The best Aleppo galls, collected in Asiatic Turkey, principally in the province of Aleppo, are collected before the insects escape. Galls are also largely imported from Persia and to a lesser extent from Greece. If collected after the insects have escaped, galls are of a pale, yellowish-brown hue, spongy and lighter in weight, perforated near the centre with a small hole. These are known in commerce as white galls.
Galls have no marked odour, but an intensely astringent taste, and slightly sweet after-taste.
English Oak Galls, or Oak Apples, are smooth, globular, brown, usually perforated and much less astringent than Aleppo Galls, containing only 15 to 20 per cent of gallotannic acid. They have no commercial value. They are not spherical, but of extremely diverse and irregular form, with a thick, grey, velvety down, making them a reddish-brown colour. They contain about 70 per cent of gallotannic acid. Mecca Galls , from Bassorah, known as 'mala nisana,' are spherical in shape and surrounded about the centre by a circle of horned protuberances.