Have You Seen the Red Lily Beetle?

Adult lily leaf beetle
Lisa Tewksbury, University of Rhode Island, Bugwood.org

The red lily beetle (Lilioceris Lilli), also known as the lily leaf beetle, is a native of Europe and was discovered in North America near Montreal in 1943. Its damage was limited to the Montreal area for decades, but recently it has spread to the south and west. Many gardeners believe it came with bulbs shipped from Europe.

The beetles are strong fliers and excellent hiders. In 1992 they had spread into Ontario and the New England States, and in 2004 they were reported in the Portage la Prairie area in Manitoba. This last year there have been 15 different sites reported in Manitoba as well as the area around Calgary, Alberta. However, not all areas are yet infested and gardeners who are transplanting bulbs should be careful not to move these beetles to an uninfected area.

The red lily beetle is an 8mm long bright red beetle with a black head and legs. The larvae have dirty orange-red bodies with black heads. The larvae usually cover themselves with their own slimy black excreta and could be mistaken for bird’s droppings. With adequate food they reach 8-10mm in length, at which stage they pupate in the soil.

Larvae
Richard A. Casagrande, University of Rhode Island, Bugwood.org

Both adults and larvae damage lilies primarily by defoliating them, but in heavy infestations the flowers seed capsules and stems will also be eaten. Although adult beetles have been found on other plant species, it is only the lilies and fritillaries which are true hosts on which eggs are laid and the larvae develop. In Canada no natural predator is known.

Control

Gardeners can control small areas by handpicking adults and eggs. Insecticides which contain extracts from the Neem tree are also effective in killing larvae and repelling adults.

Recent efforts to control the lily beetle have concentrated on biological control. The North American Lily Society has supported the scientific introduction of the biological control method using parasitoids (a moth which lays its eggs in the larvae) in the New England States over the last seven years. This study has been completed and declared a success.

At present gardeners rely on chemicals or hand picking to control this pest, but the long period over which the adults are active (late April to October) can make this difficult. Adequate control in areas where the pest is abundant may require measures to be repeated during spring and summer. In some areas of Ontario and Quebec, gardeners have stopped growing lilies due to this beetle. We know that the problem will likely become more widespread, and while we can monitor our garden lilies there is concern for our wild prairie lilies (L. philadelphicum var. andinum).

Damage caused by the lily leaf beetle
Richard A. Casagrande, University of Rhode Island, Bugwood.org

It is hoped that through a network of volunteers, the movement and activities of the red lily beetle can be monitored in Saskatchewan and thereby protect the wild prairie lily. The Saskatchewan Ministry of Environment has been made aware of this threat, and has indicated that if this invasive species is found necessary action will be taken as required.

We need your help in monitoring this pest, which you can expect to see early in the spring. Protect your lily patches and if you spot this beautiful but deadly pest, please call Dolores Nelson, South Saskatchewan Lily Society at 306-586-3697.

For more information on the beetle, including tips on how to find and remove it, please see this article from the North American Lily Society called The Lily Leaf Beetle: an unwelcome invader.