Lily leaf beetles are tiny insects belonging to the order Coleoptera. They undergo complete metamorphosis (holometabolic insects). Before reaching adulthood, they pass through the egg, larva and pupa stage.
Eggs: They are yellow, orangish or red, with an elongated capsule shape, about 1.5 mm long.
Larvae: They have a yellow body with black head and legs. They are about 9 mm long at maturity. They hide from predators under a blackish mass of mucus and excrement.
Adults: They are between 6 and 8 mm long. They have a bright red body, and their legs and pair of antennae are black.
Lily leaf beetles overwinter buried in the soil, as adults, often at the base of their favourite plants. They appear in early spring (April), to feed on the young emerging foliage and to mate.
Each female lays about three hundred eggs, attaching them in bands on the underside of young leaves. The eggs hatch after a week or two, and the newly hatched larvae feed on the plants for a few weeks. After that, they drop to the ground or descend the plant stem, and burrow into the soil to pupate, emerging as adults 4 to 5 weeks later.
The new generation of insects appears in late June or early July. The adults start seeking shelter for the winter in late July. In our climate, lily leaf beetles generally produce a single generation each year.