The head, thorax and appendages are black except for the tarsae which are brownish. The wing covers are blue with parallel sides. The front femur of the male is strongly toothed while that of the female is smooth. The oviposition site is hard to see as it becomes covered with callus. Eggs are laid into fine stems, but development is only completed in stems over 0.9 mm and the prostrate stems of non-flowering Dalmatian toadflax are not favored.
Larval survival is poor in the prostrate stems of non-flowering plants.
Presumably, the assimilates in these stems are translocated to the roots so they are nutritionally poor. It is 3.0 to 4.5 mm long, initially white but gradually turns black . Feeds preferentially on the growing leaves and stem of Linaria spp. Weevils from yellow toadflax are smaller than from Dalmatian toadflax, but egg production does not seem to be affected. Development from egg to adult takes 50-63 days.