Lily Beetle Lilioceris lilii
The Lily Beetle is scarlet on top, the remainder of the body is black. It measures around 10 mm. It feeds on all kinds of plants in the lily family, including lilies and fritillaries in ordinary gardens. Even though the adult beetles are slightly harmful, most damage is done by the larvae. Female Lily Beetles do not deposit their eggs in just one day. They may live up to 3 months, depositing just a few eggs every day. These hatch in just 6 days and larvae feed during 2 weeks. Then they pupate underground, in a hollow tree stump, or in debris. Because the female just keeps on producing eggs every day the beetles and their adults are eating plants for a long stretch: from April to September, making them very difficult to fight.
The eggs are orange and deposited in strings on the underside of lily leaves. The larvae are reddish brown themselves, but always look slimy, and greyish brown. For protection they cover themselves in their own dung. This way they look like bird droppings and are left alone by most enemies. The adult beetles taste awfully. Birds will therefor leave them alone. The last breed pupates in just two weeks, but stay in their hiding place to overwinter.
The damage to lilies and fritillaries in gardens is enormous. As beetles and larvae concentrate on eating the leaves, the plants soon look terrible. And the holes in the leaves also make the plants much more susceptible to diseases, such as mold. Good looking, big lily plants may be gone in just a month's time after getting infested. Good effective ways of control are not easy to find. In smaller gardens the best way is to catch the adults and kill them. As they are extremely easy to spot, this is a tedious, but realizable appraoch.
The Lily Beetle is also known as the Scarlet Lily Beetle, the Scarlet Leaf Beetle, the Red Lily Beetle and the Red Leaf Beetle.