Scarlet beetles (6mm – 8mm long) with black heads eat the leaves, flowers and seedpods of lilies and other members of the lily family. Don’t mistake them for ladybirds. Between April and September the beetles lay eggs on the undersides of leaves. After a week they hatch into reddish-brown maggot-like grubs, and feed on the same parts of the plant as the parents. Possibly to deter predators or disguise themselves, the larvae cover themselves in their own wet, black excrement.
Lily beetles are beautiful insects, but they’re capable of stripping lilies, fritillaries and giant lilies (Cardiocrinum) back to a few meagre stems. Watch this short Quick Tips video, with entomologist Richard ‘Bugman’ Jones, for advice on how to deal with lily beetles:
Lily beetle symptoms
Lily leaves are shredded and may be covered in brown-black droppings.
Find lily beetles on
lilies, fritillaries and Solomon’s seal
Organic ways to deal with lily beetles
Pick off the grubs and adults as soon as you see them. The adults will drop to the ground at the slightest touch, so spread newspaper under the plants to catch them. Be quick and crush them under foot or they’ll fly off.
Chemical methods of lily beetle control
At the first sign of attack, spray plants with sunflower oil. Treatment is more effective on larvae than adults.