Integrated Pest Management Program Department of Plant Science and Landscape Architecture

UConn Extension

BIOLOGICAL CONTROL OF LILY LEAF BEETLE Background. Lily leaf beetle (Lilioceris lilii) is a serious pest of many herbaceous ornamental plants. While lily leaf beetles feed on a number of plant hosts, including Lilium spp., Fritillaria spp., Polygonatum spp. (Solomon's seal,) Solanum dulcamara (bittersweet nightshade,) S. tuberosum (potato,) Smilax spp., and Nicotiana spp., they can only reproduce and develop on Lilium species, which include Turk's cap lilies, tiger lilies, Easter lilies, Asiatic and Oriental lilies, and species of Fritillaria.

Figure 1. Adult Lily Leaf Beetle Figure 2. Lily Leaf Beetle Damage

Lilioceris lilii is native to Eurasia. It was first discovered in Montreal in the 1940s. The first New England occurrence was in Boston in 1992, and lily leaf beetles were first confirmed in Connecticut in 1999. Lily leaf beetle is now found throughout New England, New York, Pennsylvania, Quebec, Ontario and through central Canada to the western coast of North America. Connecticut Presence. Lily leaf beetle has been confirmed in all eight Connecticut counties. Property owners continue to report this exotic insect pest each year. Connecticut’s natural areas contain a number of species of native lilies. Many businesses in the green industry grow and sell ornamental lilies. Nurseries and garden centers have reported problems with lily leaf beetles damaging wholesale and retail host plants.

Control Methods. There have been no natural enemies of lily leaf beetle recorded in North America. Current management approaches for lily leaf beetle include both chemical and mechanical or physical methods. Adults, larvae, and eggs can be hand-picked from plants and destroyed. Several insecticides are labeled for lily leaf beetle control, but some of these are toxic to bees and other non-target insects. With increasing trends of organic crop

production and potential bans of insecticides in the future, biological control will provide a sustainable and viable alternative. A successful biological control program may reduce the costs and environmental impacts of insecticide use and will provide a new tool to enhance management options for control of lily leaf beetle.

Figure 3. Lily Leaf Beetle Damage to Buds Figure 4. Lily Leaf Beetle Damage to Lilies in a Landscape

Figure 5. Adult Female Laying Eggs Figure 6. Larvae and Larval Damage

Biological Control. Three species of parasitoid wasps have been approved for release to help control lily leaf beetles and their damage. The parasitoid wasps lay their eggs in lily leaf beetle larvae, thereby disrupting the lily leaf beetle life cycle. Release and monitoring of two distinct biological control agents (the parasitoid wasps Tetrastichus setifer and Diaparsis jucunda) for biological control of lily leaf beetle began in Connecticut in 2012. These beneficial insects have previously been released in four other New England states (MA, ME, NH, and RI.)

Figure 7. Diaparsis jucunda Parasitoid Wasps Figure 8. Release of D. jucunda Parasitoid Wasps

Links to Additional Information on Lily Leaf Beetle:

Connecticut Agricultural Experiment Station Fact Sheet http://www.ct.gov/caes/lib/caes/documents/publications/fact_sheets/entomology/lily_leaf_beetle.pdf

Lily Leaf Beetle Online Tracker http://lilybeetletracker.weebly.com/

University of Maine Bulletin http://umaine.edu/publications/2450e/

University of Massachusetts Fact Sheet http://extension.umass.edu/landscape/fact-sheets/lily-leaf-beetle

University of Rhode Island Lily Leaf Beetle Photo Identification Guide http://web.uri.edu/biocontrol/lily-leaf-beetle-photo-identification-guide/

To view a larger, interactive map and see other aspects of the project, please visit the following website: http://arcg.is/0mDyTX

Prepared by: Gail K Reynolds and Donna Ellis, 2015; Updated 2018

Photos by: Gail K Reynolds and Donna Ellis

The information in this document is for educational purposes only. The recommendations contained are based on the best available knowledge at the time of publication. Any reference to commercial products, trade or brand names is for information only, and no endorsement or approval is intended. UConn Extension does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available. The University of Connecticut, UConn Extension, College of Agriculture, Health and Natural Resources is an equal opportunity program provider and employer.