An abnormal growth (often a swelling) of plant tissue, caused by external stimuli, generally by insects such as gall wasps (Cynipidae), and gall midges (Cecidomyidae) but also by mites, aphids, psyliids and some Lepidoptera. Sometimes galls are formed by bacteria, parasitic fungi or other diseases of the plant so galls induced by insects are called insect galls.
Links: http://en.wikiped.../wiki/Gall
Hi. Please delete all photos of E. carrapateira I've uploaded. I did not remember that I already had uploaded that species in particular. Except the pallidifacies (this was not present yet). Thank