Biological control of lily beetle

To naturally control lily beetles, encourage predators like birds, frogs, wasps, and ground beetles into the garden. 

Three species of parasitic wasps in the UK, Lemophagus errabundus, Tetrastichus setifer, and Mesochorus lilioceriphilus, feed on the larvae of lily beetle.

Plant nectar-rich, flowering plants to attract lily beetle predators, including buddleia, calendula, sedum, stock, sweet William and wallflowers. Get a head start by growing a small patch of nettles to shelter predators. Cut the nettles back when lily beetles appear in other parts of your garden to encourage the predators to seek them out.

Frogs and toads can be encouraged into the garden by providing a pond or other still water feature where tadpoles can develop. Construct the pool so at least one side gradually slopes up to dry land. This allows young amphibians to leave the water in midsummer once the tadpole stage is over. Small amphibians can be heavily predated by birds, so grow plants around the pool to provide some cover.

Provide a place for frogs and toads to overwinter. Log piles are great shelters but frogs, toads and newts will also find suitable places in hedge bottoms, compost heaps, and under stones. They may aslo hibernate in the bottom of ponds. To avoid disturbing amphibians, especially in the hibernation period, ponds should not be cleaned out unless absolutely necessary.