Red Lily Beetle

Lilioceris lilii

Red Lily Beetle, Scarlet Lily Beetle, Lily Leaf Beetle

Lilioceris lilii (1) by Gilles Gonthier (CC BY 2.0)
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An adult Lilioceris lilii lily beetle on a leaf
Lilioceris lilii (1) by Gilles Gonthier (CC BY 2.0)
1 of 12
As their name suggests, Red Lily Beetles (Lilioceris lilii) eat the foliage of lilies! They're easily recognised, with bright red elytra (wingcases) and black heads. The preferred habitat is usually gardens, and plant nurseries, or anywhere else Lillies are in high abundance. Damage is mostly aesthetic, with the flowers failing to open following heavy infestations. The larvae cover themselves in excrement to hide from predators; so they can easily be mistaken for bird droppings! This convincing camouflage strategy keeps larvae hidden from birds and other predators. It's recommended to start monitoring Lilium and Fritillaria plants from March to early September. Remember to check beneath foliage and the nooks between stems and leaves for red oblong eggs.
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Traits

A plentiful food resource for ladybird and hoverfly larvae.
These beetles can multiply quickly.

Appearance

Adults: Mature beetles are about 1cm. They are best recognised by their bright red elytra (wing cases). They have black stomachs, legs and antennae. If you see a beetle of this description near lilies, it's most likely a red lily beetle! The adults will squeak to alert their mates when threatened! Larvae: The larvae are soft-bodied, grub-like and bright red (like an adult beetle). They have blackheads with small black mouthparts. Larvae hide beneath excrement (green-brown goo!), so they can be hard to spot. Eggs: The eggs are laid beneath the leaves of Lily. They are oblong, laid in clusters of 5-10 and are also red in colour.

Symptoms

Young larvae target the tissue beneath leaves. Their feeding results in large, dried-out patches on the underside of leaves. Old larvae will demolish the whole leaf, as well as petals and stems. Adults target the leaves, petals and seed pots, leaving behind distinctive holes. If the beetles are in high abundance and plants stripped whole, then bulb health may be impacted.

Activity

Diurnal

Personality

Order

Coleoptera

Family

Chrysomelidae

Metamorphosis

Complete

Distribution

Europe

Biological treatment

In many cases, lilies and fritillaries seem to be able to withstand the damage caused by the beetle and its larvae. These beetles are active over a long period in Europe. Regularly inspect any lily plants from March through to the end of August. Make sure to check stems carefully because they like hiding in the notches of stems and leaves. Wearing some rubber gloves can make this easier, but not mandatory. For light infestations, lilies can be effectively managed by picking off beetles and eggs whenever seen. They can be squashed, relocated or put on a bird table. The 'Defender Pink' lily is believed to be Lily Beetle tolerant. If plants seem to be regularly attacked by this insect, the latter may be the most feasible option.

Chemical treatment

Grazers G4 is thought to be a more environmentally benign treatment to tackle Red Lily Beetles. Please read the labelled bottle carefully before applying to plants. Neem oil can be applied as an alternative to the latter. It's not appropriate for use if the lilies are near a water body because it can be toxic to aquatic wildlife. There are also more persistent chemicals available for use on the market. Lambda-cyhalothrin, deltamethrin, and cypermethrin are a few of the active components that can eliminate Lily Beetle larvae. The latter should only ever be used if an infestation is considered heavy. Likewise, any plants that are in flower, or near a water body, should never be sprayed by the latter to protect pollinating insects. It's best to apply insecticides earlier in the season when larvae are most active. Assess whether chemical treatment is essential. Towards the end of the warmer season, Lily Beetles begin to move away from lilies to overwinter. Applying chemicals at this point would be ineffective and wasteful! Please read and follow the manufacturer's instructions before any products are used.

Attracts

Food plants include various Liliaceae, especially for plants in the Lilium and Fritillaria genera.

Repels

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