Lily beetle: dealing with attacks

How to recognise the lily beetle?

The presence of the lily beetle can be noted in two ways:

• by observing it: it is a beautiful small bright red beetle, about 1 cm long, with black legs, abdomen, and long antennae. It is often seen on the underside of leaves from March to October. The small bright orange eggs of the lily beetle can also be observed on the underside of leaves: they are aligned in small groups along the veins. They hatch into black and orange larvae, which cover themselves with excrement to hide and protect themselves from the heat.

• by its effects: its larvae eat the roots of lilies, and the adults devour the leaves, making holes in them, as well as the flowers and flower buds. The plants decline and eventually die if the attack is not contained.

Unfortunately, all varieties can be affected, but the candidum lily is among the most vulnerable, while Martagon lilies are somewhat less attacked. The beetle also targets, to a lesser extent, alliums, fritillaries, and the giant Cardiocrinum lily.

Lily beetles reproduce very quickly. A female can lay up to 400 eggs per season. Therefore, as soon as you see the first beetles, it is important to act immediately to curb their population.

What are the natural treatments for lily beetle?

The most effective method is the manual collection and destruction of adults. To curb the attack, it is ideal to check every day, early in the morning, for several weeks. Be careful, when trying to collect them, the vine-plants tend to drop to the ground on their backs to become less visible… Collecting the eggs and larvae is also possible. Remember to turn the leaves over to look for the orange eggs on their undersides.

You can also collect and burn the leaves affected by the larvae.

Some apply coffee grounds at the base of the attacked stems, or spray a solution made from pyrethrum or neem oil. It is also possible to spray an infusion of tansy, whose smell repels the vine-plants. However, to date, no treatment has proven to be completely effective. We therefore recommend prioritising manual collection.