Lily beetle: how to recognise and treat it

Pest

Symptoms

Bright red beetles about 8 mm long with a black head and legs make rounded holes in leaves and also eat petals and seed pods.
Rotund reddish-brown larvae hidden under their own wet black excrement; young larvae graze the leaf undersides, leaving white or brown dried patches, older ones eat whole leaves from the tip back.
Clusters of orange-red, sausage-shaped eggs on the leaf undersides; heavy defoliation in early summer leaves undersized bulbs that may not flower next year.

Handpick beetles, larvae and eggs from spring onwards (wear gloves for the larvae) and destroy them.
Neem oil (azadirachtin) or insecticidal soap gives some control of young larvae when applied every 5–7 days after the eggs hatch.
Encourage birds, frogs, ground beetles and wasps, which eat the larvae; where specialist parasitoid wasps occur, avoid disturbing the soil of lily beds.

Contact insecticides with deltamethrin, lambda-cyhalothrin or pyrethrins act on the larvae; spray only foliage, never open flowers, late in the day when bees are not active, and follow the label.

Reference information, not a guarantee. Read and follow the label of any product: dose, safety and the days to wait before harvest.

Start checking lilies and fritillaries from late March, when the beetles emerge; treating the soil under the plants is pointless, as adults overwinter elsewhere.
Check leaf undersides for rows of orange-red eggs and crush them.
Prefer less susceptible lilies — some Oriental lilies, Lilium henryi, L. regale and 'Defender Pink' show resistance or tolerance; Asiatic hybrids are susceptible.

Figures checked against these sources.