Lily beetle

Lilies (Lilium species and hybrids), Giant lilies (Cardiocrinum species) and fritillaries (Fritillaria species) can be extensively defoliated by the common and widespread insect known as lily beetle or red lily beetle.

Red lily beetle

Quick facts

Common name Red lily beetle or lily beetle
Scientific name Lilioceris lilii
Plants affected Lilies (Lilium) fritillaries (Fritillaria)
Main symptoms Foliage is eaten by red beetles and their black excrement-coated grubs
Most active Late March-October

What is red lily beetle?

Lily beetle and its larvae are leaf-eating insects of lilies and fritillaries. The adult beetles are very occasionally found on other plants but lilies and fritillaries are the only plants on which eggs are laid and the grubs develop. Apart from spoiling the plants' appearance,  attacks in early summer can result in undersized bulbs developing, which may not flower next year. Lily beetle has become widespread in the UK over the past three decades.

Survey

Seen the lily beetle? We would like to know.

As part of RHS research we would like to know where the lily beetle has been seen.

Please submit your records via our lily beetle survey (expected time to complete survey = two minutes).

Thank you to everyone who has submitted records – read a blog about the surveys

Watch an animated map of the results from the lily beetle survey (links to YouTube) 

Symptoms

Most gardeners first become aware of the presence of lily beetle when their plants are stripped of foliage. Look out for;

  • Adult beetles which are 8mm long and have bright red wing cases and thorax. The head and legs are black
  • Clusters of orange-red, sausage-shaped eggs on the undersides of leaves
  • Larvae which reach 6-8mm long and are rotund, reddish brown with black heads. They are usually completely hidden under their own wet black excrement
  • Young grubs graze away the underside of leaves, resulting in white or brown dried up patches. The older grubs eat entire leaves, starting at the tips and working back to the stem, they will also feed on petals, stem and seed pods 
  • Adult beetles make rounded holes in the leaves and will also feed on petals and seed pods

Adult lily beetles mating
Lily beetle eggs on the underside of a leaf
Lily beetle larvae
Lily beetle distribution in the UK (produced using ©DMAP)
    Adult lily beetles mating Lily beetle eggs on the underside of a leaf Lily beetle larvae Lily beetle distribution in the UK (produced using ©DMAP)

    Control

    Non chemical control

    Where only a few lilies and fritillaries are being grown, the plants should be regularly inspected from late March onwards so that adult beetles, larvae and eggs can be removed by hand. The lily 'Defender Pink' is advertised as lily beetle tolerant.

    Chemical control

    • Pesticides are likely to be more effective on larvae than adults
    • Heavy infestations which are impractical to remove by hand can be treated with pesticides
    • Organic insecticides containing natural pyrethrins (e.g. Bug Clear Gun for Fruit or Defenders Bug Killer, ecofective Bug Killer (also contains fatty acids)). Several application of these short persistence products may be necessary to give good control
    • Synthetic pyrethroid pesticides such as lambda-cyhalothrin (e.g. Westland Resolva Bug Killer), or deltamethrin (e.g. Bayer Sprayday Greenfly Killer) can be used
    • The systemic neonicotinoid insecticide acetamiprid (e.g. Bug Clear Ultra) can also be used 
    • Plants in flower should not be sprayed due to the danger to pollinating insects
    • Inclusion of a pesticide product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener

    Download

    Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)

    Biology

    Red lily beetle overwinters as adult beetles in soil, leaf litter and other sheltered places. This could be anywhere, not necessarily in the vicinity of lilies and fritillaries. Consequently, there is no advantage in attempting to treat the soil below lily plants. The beetles begin emerging on sunny days in late March and April when they seek out the foliage of host plants.

    Eggs are laid in small batches on the underside of leaves during April to mid-summer. The eggs hatch and the larvae feed on the foliage. When fully fed, the larvae go into the soil to pupate. The next generation of adult beetles emerges from mid-summer onwards. These beetles add to the feeding damage but there is only one generation a year and these late summer adults will not mate and lay eggs until the following year.

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