Nature on our doorsteps: Lily Beetles

Rosaleen Dwyer is the County Heritage Officer at South Dublin County Council – every week she gives us an insight into nature on our doorsteps and the beautiful biodiversity of its plants and wildlife.

THE Lily Beetle is a small, bright red, insect belonging to the group of beetles known as the leaf beetles.

Its name indicates that this particular leaf beetle feeds on the leaves of Lily plants.

The beetle is approximately 6-8mm long and has a distinctive bright red body with a contrasting black head, black legs and black antennae.

The Lily Beetle is not native to Ireland. Its natural range is across the European and Asian continents.

It was first recorded in the southern part of Britain in the 19th century, but it is only in the last twenty years or so that it appears to be spreading rapidly northwards and westwards, including into Ireland.

The native Red Soldier Beetle should not be mistaken for the invasive Lily Beetle

This rapid expansion may be linked to warming weather conditions which suit this species of leaf beetle.

Like most beetles, it can fly, and this helps it to move to new areas. Its larvae also hide in the plant’s bulbs, and it is most likely that the species arrived in Ireland through the importation of commercial Lily bulbs.

The distinctive red adult beetle may be spotted from the month of March until early autumn.

The female beetle lays her eggs on the leaves of a Lily plant and when the larvae hatch out, they begin to feed, eating their way from the tip of the leaf to the plant stem.

A large infestation of larvae can result in the loss of all the plant’s leaves.

This loss prevents the plant making food for itself, food which it needs to produce this season’s flowers and also to store in its underground bulbs for next year’s growth.

After an attack by the Lily Beetle, the plants often fail to flower the following year.

Unlike in Britain, Ireland does not have many wild members of the Lily family to be impacted by this beetle.

The beetle’s spread in Ireland is therefore likely to affect cultivated garden Lilies mostly.