Research

Red lily beetle

Predators and parasites

In parts of mainland Europe the lily beetle is kept in check by four species of parasitic wasp that attack the larval stage, only one of which (Tetrastichus setifer) was known to occur in the UK. Research at the RHS found a second species of parasitic wasp (Lemophagus errabundus) in Britain in 1999. The continuing prevalence of this beetle as a pest would indicate that the parasitoids present in the UK are not sufficient to prevent this beetle causing problems.

Risk to lily growers

The surveys found that a quarter of those who had experienced a problem with the beetle, would reduce or stop growing lilies. It was also established that lilies grown under any regime, including under glass can be susceptible to damage. The primary conclusions were that the beetle problem is likely to get worse as the beetle continues to spread throughout Britain. This is likely to result in increased insecticide use. However, despite many end-users of lilies stating they would stop growing lilies, lily suppliers indicated that sales have increased.

Download the risk assessment report (Adobe Acrobat pdf 245KB)

Odour mediated behaviour

A major part of the research degree had the objective of investigating the beetle’s odour mediated behaviour. Such research is vital if the long term aim of developing a control of the beetle using odours (volatile chemicals) that the beetle responds to is to be developed.

Results from the experiments indicate that in the spring female beetles are able to locate lilies by odour alone, and that the beetles preferentially move towards the odour of plants already infested with other beetles. This part of the work is being prepared for publication, a summary of results will be presented when the work is finished.

Control

At present gardeners rely on pesticides or hand picking to control this pest, but the long period over which the adults are active (late March to October), can make this difficult. Adequate control in areas where the pest is abundant may require measures to be repeated during spring and summer. Find out more about control from the RHS Advice profile on lily beetle

Publications by RHS staff

Fox Wilson, G. 1942. The Lily beetle, Crioceris lilii . Journal of the Royal Horticultural Society . 67 : 165 - 168.

Fox Wilson, G. 1943. The lily beetle, Crioceris lilii Scopoli: its distribution in Britain (Coleoptera). Proceedings of the Royal Entomological Society of London. (A) 18 (10-12): 85-86

Halstead, A J. 1989. On the Move? The Garden 114 :321-323

Halstead, A J. 1990. Lily beetle survey. The Garden 115 : 439

Salisbury, A. 2003. Two parasitoids of the lily beetle, Lilioceris lilii (Scopoli) (Coleoptera : Chrysomelidae) in Britain, including the first record of Lemophagus errabundus Gravenhorst (Hymenoptera : Ichneumonidae). British Journal of Entomology and Natural History 16 : 103-104.

Salisbury, A. 2003. A further note on the continued spread in Britain of the Lily Beetle Lilioceris lilii (Scopoli) (Chrysomelidae), with notes on its host plant range. The Coleopterist 12 (2): 67-76

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