Lily beetle
Lilioceris lilii
also called Scarlet lily beetle, Red lily beetle
Brilliant scarlet beetles and their slimy black larvae that strip lilies and fritillaries in weeks. Hand-pick adults and larvae from April onward — check leaf undersides.
How to know it
An unmistakable beetle 6–8 mm long, brilliant sealing-wax red with a black head and legs. The larvae are orange grubs that plaster themselves in their own black excrement, so what you actually see is a slug-like smear of wet droppings moving along the leaf.
What you'll see
- Scarlet beetles sitting openly on lily and fritillary leaves from April.
- Wet black smears on leaves and stems — the larvae under their excrement coats.
- Leaves eaten from the edges in, then stems, buds and flowers.
- A lily reduced to a bare stalk within a fortnight of the larvae hatching.
- Beetles dropping to the ground and landing red-side-down the instant you reach for them.
Where it comes from
Adults overwinter in soil and leaf litter — often nowhere near a lily — and emerge from March to April. Females lay lines of orange eggs on the leaf undersides; larvae feed for two to three weeks, pupate in the soil, and a new generation of adults emerges to feed on into autumn.
Any garden growing lilies within the beetle’s now very wide range. It has no meaningful natural enemies here, so numbers depend almost entirely on how diligently you pick.
Dealing with it
- Hand-pick from the moment shoots appear in spring, and cup a hand beneath first — a disturbed beetle drops and vanishes.
- Wipe the larvae off leaf undersides with a gloved thumb; they are stuck in place and easy to remove.
- Rub off the orange egg lines whenever you check the plants.
- Check every few days through spring — this is a pest that vigilance genuinely controls.
- Skip sprays on plants in flower; the beetles are far easier to reach by hand than any spray will be.
Keeping it out
- Inspect the compost of bought lily bulbs and pots, where overwintering adults hitch a ride.
- Grow lilies in pots you can inspect closely, and change the top compost each spring.
- Clear leaf litter around lily beds in late winter.
- Grow fritillaries and lilies apart from each other so an outbreak cannot walk between them.
- Accept some damage on established clumps rather than spraying; the bulbs usually rebuild.
What it goes for
Lilies and fritillaries above all; occasionally nomocharis, cardiocrinum and lily-of-the-valley.
See also
The Cottage Garden Companion — the gardener's bestiary at cottagegardencompanion.com