Eteobalea intermediella and E. serratella are very similar, differing mainly in their egg appearance, egg-laying behavior, and number of generations per year. Adults are slender, 8–10 mm long, and are black with white and yellow spots. Adults emerge in late spring, and females lay up to 180 eggs in loose strings of 3–8. Eteobalea intermediella lays eggs in the lower leaf axils or on the base of yellow toadflax and non-flowering Dalmatian toadflax stems. Eteobalea serratella lays eggs at the base of yellow toadflax stems or on the soil surface at the base of toadflax stems. The pattern on the surface of E. intermediella eggs is net-like while the surface of E. serratella eggs has a ridged appearance, marked by fine parallel lines or furrows. Larvae bore into the root crown where they feed on tissue inside tunnels they carve and line with silk. Larvae are cream-colored with brown head capsules. They develop through five instars and are up to 12 mm long. E. serratella has one generation per year while E. intermediella has two; second generation adults emerge in mid-summer. Mature larvae of both species overwinter in roots then pupate in spring inside cocoons within the root crown.