The red or scarlet lily beetle (Lilioceris lilii) has become the lily growers’ nemesis. Both the adults and larvae can defoliate lilies (Lilium and Cardiocrinum) and fritillaries (Fritillaria).
Adults are 8mm long, bright red with a black head and legs.
Eggs are 1mm long and orange-red, found in groups on the underside of lily and fritillary leaves.
Larvae have orange bodies with black heads but are normally covered with their own slimy black excrement. The fully grown larvae are 8-10mm long. The pupal stage is in the soil.
The beetle became established in Surrey in 1939 and it remained confined to south east England until the late 1980s. By the end of 2011 it had become widespread in England and Wales and was spreading in Scotland and Northern Ireland, it is also beginning to spread in the Republic of Ireland.
Adult lily beetles emerge from overwintering sites from late March to May. They feed and lay eggs on the underside of leaves of host plants from late April until early September. The eggs hatch after approximately a week. The larvae can be found feeding on the foliage between May and the end of September. After about two weeks, when the larvae are fully grown, they pupate in the soil. Two to three weeks later new adults emerge. Despite claims in some literature, the lily beetle has only one generation a year. The beetles overwinter as adults in sheltered places, often in the soil but not necessarily near lilies or fritillaries.
Both adults and larvae damage lilies (Lilium and Cardiocrinum spp and hybrids) and fritillaries (Fritillaria spp.) primarily by defoliation, but in heavy infestations the flowers, seed capsules and stems will also be eaten. Although adult beetles have been found occasionally feeding on other plant species, only lilies and fritillaries are true hosts, on which eggs are laid and larvae develop.
The lily beetle has been observed on 82 hybrid Lilium, 30 Lilium species, one Cardiocrinum species and seven Fritillaria species.
Download the lily beetle host list
As part of RHS research, the susceptibility of six different lilies was assessed (one species and five hybrids). Results from the trial indicated that the species lily Lilium regale was less susceptible than the hybrids. The results from the trial have been published - see . Salisbury A, Clark S J, Powell W, and Hardie, J. 2010. Susceptibility of six Lilium to damage by the lily beetle, Lilioceris lilii (Coleoptera; Chrysomelidae). Annals of Applied Biology 156: 103–110.
The lily beetle is not native to the UK; it has been accidentally imported into Britain on several occasions. It was first noticed at the end of the 19th century, with a handful of short-lived infestations in England and Wales. However, it was not until 1939 that an established colony was discovered in a private garden at Chobham, Surrey.
By the late 1950s the beetle had become widespread in Surrey and was also found in Berkshire. By 1990 the beetle's range had expanded into Hampshire, Middlesex, Wiltshire, Dorset, Hertfordshire and Oxfordshire. During the 1990s and 2000s the beetle was reported from many new areas of England and Wales and by the end of 2009 it had been found in all English counties. In 2002 the beetle was reported for the first time from Glasgow and Belfast. Continued reports to the RHS indicate that the beetle established and spreading in Scotland and Northern Ireland. The first report of the beetle from the Republic of Ireland was received during 2010.
The lily beetle is native to Eurasia, although it is currently impossible to know exactly where. Lily beetle is also established and spreading in North America and it is now found almost everywhere that lilies are grown in the northern hemisphere.
The increase in the distribution of lily beetle over the past two decades has been coupled with a rise in its frequency as an enquiry made to the RHS Members’ Advisory Service. Before 1980 lily beetle enquiries made up less than one percent of all pest enquiries received, but during the past two decades the proportion of enquiries has increased to more than three percent.