Insect

Lily Leaf Beetle

The lily leaf beetle is thought to be native to Asia. It was first discovered in North America in Montreal in the 1940s and has since spread throughout the U.S. and Canada. They feed on members of the Lillium and Fritillaria genera, but often will "taste" other plants (e.g. bittersweet, potato, hollyhock, hosta spp.) but most damage will occur on true lilies and their close relatives.

Identification

Here are some key features that may help positively identify the lily leaf beetle in its various life stages:

Eggs:
  • Eggs are small and reddish-orange
  • Laid in irregular lines of 3-12 eggs on the underside of leaves
  • Eggs are only laid on true lilies and fritillary
  • Females can lay 200-300 eggs that hatch 8-10 days later
Larvae:
  • Most destructive stage
  • Have a slug-like appearance, yellow-white to orange in colour with a black head
  • Cover themselves with their own excrement to deter predators and protection from the sun
  • Feed voraciously on foliage for 16-24 days
  • Often found on the underside of leaves
  • Rapidly defoliate plants by eating leaves, buds and flowers
  • Mature larvae crawl down the plant and pupate in the soil
Pupae:
  • Fluorescent orange colour inside a waterproof cocoon
  • Pupation takes about 20-22 days
  • When the adult emerges, it digs its way out of the soil and feeds on lilies until the fall
Adults:
  • Bright, scarlet red beetle with black head, antennae, legs and underparts
  • Less than 1/3" or 6-8 mm long
  • Squeak when squeezed
  • Spend winter months in the soil beneath host plants
  • Emerge in early spring (late April to early May) to forage and mate
  • Feed on young lily leaves
  • Strong fliers - can disperse over long distances

Information from the City of Charlottetown's Invasive Insect Species Fact Sheet

Image gallery
Lily leaf beetle adult. Photo by Green Thumb Photography.
Lily leaf beetle adult. Photo by Green Thumb Photography.
Lily leaf beetle adult feeding damage. Photo by Green Thumb Photography.
Lily leaf beetle adult feeding damage. Photo by Green Thumb Photography.
Lily leaf beetle maturing eggs. Photo by Green Thumb Photography.
Lily leaf beetle maturing eggs. Photo by Green Thumb Photography.
Lily leaf beetle feeding larvae. Photo by Green Thumb Photography.
Lily leaf beetle feeding larvae. Photo by Green Thumb Photography.
Lily leaf beetle larva mature. Photo by Green Thumb Photography.
Lily leaf beetle larva mature. Photo by Green Thumb Photography.
Lily leaf beetle feeding damage to plants. Photo by Green Thumb Photography.
Lily leaf beetle feeding damage to plants. Photo by Green Thumb Photography.
Lily leaf beetle eggs, damage, young larvae. Photo by Green Thumb Photography.
Lily leaf beetle eggs, damage, young larvae. Photo by Green Thumb Photography.