Liljebaggar

The Liljebagge: A Bright but Devastating Lily Pest

Introduction

For many garden enthusiasts, few things are as frustrating as discovering the telltale holes in the fresh leaves of their beloved lilies—clear evidence of an attack by the liljebaggen, or lily beetle (Lilioceris lilii). Once noticed, these beetles have often already left considerable damage, and their persistence makes them one of the most formidable enemies of the lily grower.

Appearance and Behavior

The liljebagge is a brilliantly red bug, 6–8 mm long, with a black underbelly—a member of the leaf beetle family (Chrysomelidae). Its vivid color makes it easy to spot when basking in the sun, though the beetle’s natural defense is to swiftly drop to the soil and show its dark underside when threatened, blending into the earth and becoming almost invisible. If you wait quietly, the beetle will start moving again, often trying to burrow into the ground; this is your chance to catch it.

When squeezed, the beetle can emit a high-pitched squeak—hence its nickname "liljetuppar" (meaning “lily rooster”) in some languages.

Life Cycle

The adult liljebagge overwinters in the ground, and as soon as the spring sun warms the soil, it emerges—not only to feed but also to seek a mate. Remarkably, the beetle can fly, making containment challenging. Soon after mating, the female lays clusters of orange eggs on the underside of lily leaves; these eggs hatch after about two weeks. In good seasons, the cycle may repeat, with up to two generations developing in a single summer.

The larvae are especially troublesome—gluttonous, slug-like creatures that cover themselves in their own reddish-greenish-black excrement, camouflaging themselves as slimy clumps beneath the leaves and devouring spectacular amounts of plant tissue. Should you do nothing, the larvae will rapidly skeletonize your lilies, leaving nothing but bare stems behind.

Host Preferences

While madonna lilies (Lilium candidum) and martagon lilies (Lilium martagon) are among the beetle’s favorite targets, virtually any type of lily can fall victim to attack. Even tougher, more leathery species such as Lilium speciosum, which often grow in shadier corners, are not immune—though perhaps less preferred, the liljebagge will still gnaw on them. The same goes for other lily relatives like different kinds of Fritillaria, including both crown imperial and snake’s head fritillaries; these, too, are frequently eaten.

Control Strategies

Manual Controls

• The most effective and environmentally responsible first step is to carefully inspect your plants in the morning or evening, when beetles are less active, and gently pick both adults and larvae from the leaves. Gloves and a bucket of water (or a jar with a splash of denatured alcohol) make this less unpleasant. The beetles can be drowned or squashed on a hard surface—if you’re squeamish, the alcohol method means you don’t need to touch them directly.
• Remove the orange egg clusters from the leaf undersides regularly to break the breeding cycle.
• For larvae hiding in excrement, sturdy rubber gloves and a bucket of water will let you strip the slime off and dispose of it—a hard stomp afterwards ensures nothing survives.

Physical & Preventive Measures

• Some gardeners report that a ring of coarse gravel or sand surrounding the lilies may discourage beetles or make it harder for larvae to pupate in the earth—results are varied, but it’s an easy and chemical-free method worth trying.

Chemical Controls

• If hand-picking isn’t possible, you may use insecticides such as Provado spray (imidacloprid-based) on the leaf undersides—particularly against larvae and eggs, which cannot be deterred by physical barriers.
• The ant remedy "Myrr" has also been reported effective when sprinkled around affected lilies, especially after knocking adult beetles onto the ground.
• Research from the Swedish University of Agricultural Sciences (SLU) suggests that Biomin may have some effect, but chemical use should always be measured and mindful of pollinators and beneficial insects.

Biological Controls & New Developments

• In continental Europe, several parasitic wasp species are showing promise as natural enemies of the lily beetle, parasitizing eggs and larvae with good success. However, these are not always present in every country or region.

Conclusion

If you grow lilies or Fritillarias, the liljebagge is a foe you’ll almost certainly meet. Vigilance and persistence are essential—the beetle’s beauty belies its destructive appetite. Whether using manual methods, barriers, careful chemical interventions, or exploring natural solutions, success often comes with a mix of several strategies. Above all, act early each season and check regularly, as neglect will quickly lead to ruined plants.

Lycka till med jakten! (“Good luck with the hunt!”)

Liljebaggar på äventyr

Liljebagge, Lilioceris lilii