LILY LEAF BEETLE
Lilioceris lilii

Name and Family
History
Identification Guide
What it does in the ecosystem
Management
Map
Image Gallery
References

Name and Family

Lily Leaf Beetle, Lilioceris lilii, is a member of the leaf beetle family (Chrysomelidae).

History

The lily leaf beetle is 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.

Identification Guide

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 fritillaria.
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.

What it does in the ecosystem

They feed on members of the Lillium and Fritillaria genera, but often will “taste” other plants (e.g. bittersweet, potato, hollyhock, hosta spp.)
Most damage will occur on true lilies and their close relatives.
All members of these groups, both native, invasive, and ornamental are affected.
Between beetles and larvae, the entire plant (leaves and flowers) can be stripped off leaving only the upright stem.
The beetles are strong fliers and can move long distances.

Management

GENERAL CONSIDERATIONS

Before selecting a control method consider:

The size of the infestation,
Resource availability.
The amount of effort you are willing and/or able to expend.
Often, multiple control methods are used simultaneously.
Consider the local ecosystem and what other organisms or ecological processes may be affected by management.

While the lily leaf beetle (LLB) is generally considered a horticultural pest, it has been reported to feed on native lily species as well. Many native lilies are considered threatened or endangered. This means that the potential management of LLB on native species should be undertaken with care and diligence to avoid additional negative effects on the lilies.
Check in with any neighbours growing lilies to coordinate your removal efforts and avoid the re-emergence of beetles from a neighbouring garden.
If you are aware of LLB in the area, it can be dangerous to move soil or share plants. This is because LLB pupate in the soil, and can hitch a ride and hatch where they are transported.

PHYSICAL CONTROL

The simplest way to eradicate LLB for small and medium-sized infestations is to manually remove the beetles, larvae, and eggs from the infested plants.
Hand pick the adult beetles.
- They can be found on any part of the plant.
- Take care to not shake the plant as the beetles are sensitive to movement and will jump off the plant when startled.
- Beetles can be squashed or put in soapy water.
- Don’t leave squashed adult beetles on the ground as they may attract more beetles.
LLB eggs are small, oblong and orange.
- They are laid in lines on the underside of the leaf.
- Sliding you fingers together along the leaf surfaces will squash them.
The larvae are also often on the undersides of the leaves but can be found on other plant parts as well.
- Either squash them or put them in a jar of soapy water.
- Be careful touching the larvae! They store their excrement all over their backs as a shield against predators. You may want to use latex gloves.
Do not focus your efforts solely on the adults, as larvae and eggs will become adults soon too.
Learn to properly identify all life stages to avoid damaging native insect populations.
Hand-picking must be repeated regularly from April to October to achieve positive results.
Females can lay 300 eggs at a time that hatch within 10 days, so you will have the challenge of managing LLB’s high reproductive rate along with quite continuous hatching.
Monitor the plants during the following growing season to ensure control efforts were effective.

CULTURAL CONTROL

If the infestation appears too daunting to tackle by hand, consider removing your lilies and planting other plants that are unaffected by the beetle.

These beetles are pests of true lilies (members of the Lilium genus that grow from bulbs) and Fritillaria spp.
Daylilies are not members of either of these groups and are thus unaffected by LLB. Any other native species not found in Lilium or Fritillaria can be a suitable alternative in the effort of keeping LLB away.
Once the area is infested will LLB it is highly unlikely that it will disappear. This is especially true in an urban or highly populated area. After your management, you may replant your lilies, but you will always need to check them for signs of a new infestation.

Chemical control methods exist, but the PEIISC does not offer advice on chemical control measures at this time. If using chemical controls, it is imperative that all local legislation and manufacturer’s instructions be followed during application.

BIOLOGICAL CONTROL

A set of three parasitoid wasps that prey on the LLB have been released in the Northeastern United States and have been found to effectively reduce lily leaf beetle numbers.
These species are not available to the general public.
Any releases of biocontrols are only to be undertaken by professionals after extensive research and regulatory review.

DISPOSAL

Ensure that you do not move any beetles with you when leaving the site and that all picked beetles, eggs, and larvae are dead.
Dispose of the insects in a sealed container, preferably a clear plastic bag, and place them in the waste bin.