Eggs are deposited on the surface of the buds situated on the tips of the main and side shoots of Russian knapweed. Larval feeding causes stunted growth of the shoot and a growing together and fusion of leaves, resulting in a so-called ‘rosette gall’ (Ananthakrishnan, 1984).
Larvae develop in silky webs between the growing leaves of the rosette gall. Dissection of field-collected galls revealed up to 14 larvae feeding inside galls induced by J. ivannikovi. ... Pupation occurs inside the rosette gall. Four to five partially overlapping generations, each about one month long, have been observed. The gall midge hibernates in the pupal stage inside galls.