Red Lily Leaf Beetle
(also known as the Scarlet Lily Beetle, Lily Leaf Beetle or Asiatic Lily Beetle)
Origins: The red lily leaf beetle is an insect native to mainland Europe and Asia but not the British Isles. It was found in Montreal (QC) in 1945 and since then has been reported throughout Ontario where lilies are grown.
Description: The adult’s bright red body (wing covers) is shiny and bright red, contrasting with the beetle’s black legs, head and underside. The beetle varies in length from about ¼” to 3/8” (6 to 8 mm).
The adult beetle overwinters in the soil or plant debris. In the early spring, the adults emerge to mate and lay their eggs. The adult lays reddish-orange eggs on the underside of the leaves of Lilium or Fritillaria which hatch into larvae that look like 3/8” slugs (8-10 mm) coloured dark orange with black heads. The larvae cover themselves with their own black slime, which apparently repels predators. The newly hatched larvae feed on the underside of leaves while mature larvae feed on the upper surface of the leaves.
The larvae cause most of the damage and spend 2-3 weeks stripping the foliage, then the flower buds before dropping to the soil to pupate. After 2-3 weeks, the adult beetles emerge to start eating again. This process occurs from early spring to mid summer. There are between 1-3 generations per year.
Host Plants: The Red Lily Leaf Beetle is a pest of the Lily species (Lilium), Lily of the Valley (Convallaria), Solomon’s Seal (Polygonatum) as well as the Fritillary (Fritillaria). The removal of the leaves deprives the plant of food production, which severely weakens it and may prevent flowering the following year, or in severe cases, kill the plant.
Treatment: Hand-picking should be the first level of control if possible. Constant vigilance and quick removal ad disposal of beetles, eggs and larvae can control an infestation a small number of plants. Try placing a light coloured cloth at the base of your lilies, so if the adults fall off and land tummy side up, you are able to see them. Make sure they are actually dead! Drop them into a can of water with vegetable oil on the top to be sure! When transplanting susceptible plants, care must be taken not to introduce the beetles to a new location.