The red lily leaf beetle (RLLB) is a European and Mediterranean beetle that feeds primarily on plants in the lily family. Known hosts are true lilies (excluding daylilies) and particularly the Asiatic lilies and fritillaries. RLLB feeds on other plants in the Liliaceae family such as Polygonatum spp. (Solomon’s seal), Smilax spp.; and on Nicotiana spp. as well as Solanum spp., such as bittersweet nightshade and potatoes. They feed on all the above ground plant parts: leaves, stems, buds and flowers, contaminate hosts with unsightly black frass, and can cause rapid death of plants.
RLLB entered North America via Montreal in 1945. In 1992, it was found in Cambridge, Massachusetts and since then has spread (and been limited) to seven east coast states. In 2012, RLLB was found in Bellevue, Washington. This pest is most likely to have a substantial impact on the economics, markets, and pesticide use for lily bulb producers, cut flower growers, lily enthusiasts and the native host plants.
Pest description and damage The RLLB is bright red and shiny—like red lacquer jewelry. It is 0.25 to 0.375 inch in length with black head, legs, underside and antennae. Adult beetles can stridulate (squeak) when disturbed. The eggs are initially bright orange when laid, then turn to a reddish-brown. Larvae are initially reddish, but later turn to a slimy black as they cover themselves with excrement. Adult RLLB damage consists of chewed leaf edges and holes in the center of the leaf. Young larval RLLB feed by scraping the tissue from the leaf surface and turning the leaf to a slimy mush. More mature larvae chew larger holes in the leaf surface.
Biology and life cycle The RLLB in Bellevue overwintered as an adult in ground litter and emerged with warm weather in late March. Female beetles are capable of laying more than 400 eggs in small groups. In Bellevue, RLLB began laying their red eggs as soon as they emerged in the spring. Eggs are laid in small clusters on the leaf surface. Eggs hatch into larvae that begin feeding on the leaf surface. When mature (3-4 weeks), larvae drop to the soil and form a cell in which they pupate. The next generation of adults emerges about 2-3 weeks after that.
Pest monitoring Begin watching for holes or specks of black frass on the leaves, or the RLLB adults as soon as the weather warms from mid-March, or when lilies begin to emerge from the soil. In Bellevue in 2013, beetles were found on March 25th when host lilies were barely two inches out of the ground. The beetles may also hide underneath the leaves. If there are several lily plants of high value and early damage is severe, pesticides may be necessary. The best time for control is when larvae are small and vulnerable. Be sure to check less favored, but acceptable, hosts such other lily relatives, nightshade, nicotiana or potato. In Washington, if homeowners suspect they have a RLLB, they should capture an image if possible and report findings to the WSDA exotic pest survey at: https://agr.wa.gov/departments/insects-pests-and-weeds/insects/exotic-pests.
Management—cultural and physical control
Minimize planting lilies in contiguous plantings. Mixed plantings make it more difficult for beetles to find new host plants. Asiatic hybrid varieties of lilies are most susceptible. Oriental varieties as well as Lilium henryi ‘Madame Butterfly,’ L. speciosum ‘Uchida,’ L. ‘Black Beauty,’ L. regale and L. ‘Golden Joy’ are reported to be resistant varieties to this pest.” Hand pick and kill any beetles, eggs or larvae.
There are no parasitoids for this insect that are native to North America. However, parasitoids in the families Ichneuonidae and Eulophidae are known from the beetle’s native lands. Several parasitoids of the red lily leaf beetle from Europe have been imported and released in the east coast states with some success.
See “Leaf feeding beetles” in Table 2:
Murray, T.A., E. LaGasa and J. Glass. 2012. Pest Alert: Red Lily Leaf Beetle. WSU Extension.