With the weather turning warmer, the emergence of Lily Leaf Beetle (LLB) has been reported already. If you grow lilies, this is a pest to watch out for in the garden! This incredibly destructive insect is originally native to Europe, was first found in Wisconsin in 2014, and confirmed in Outagamie County in 2020.
LLB is most destructive to lilium species, this includes Tiger lilies, Easter lilies, Asiatic and Oriental lilies; Hemerocallis (daylilies) are not a host for LLB. Occasionally the insect is known to feed on lily of the valley, solomon's seal, bittersweet, hollyhock, and a few species of hosta.
Adult beetles are about 1/2” long and bright red with black legs. When lilies begin to break dormancy, LLB emerge to start feeding and reproducing. They lay eggs that are irregularly shaped and appear in tan colored lines, turning orange to deep red in color as they mature. Once hatched, the larvae are slug-like and can look like globs of animal excrement. Both the larval and adult stage of the insect feed on the foliage of the lilies, oftentimes only leaving behind bare stems. This is detrimental to the lilies, as they often will not have enough energy to overwinter. LLB are strong fliers and can easily move from one area to another.
Control Methods:
Hand picking- If there are a small number of lilies, hand picking may be a suitable option. Simply remove them from the plant (both larvae and adults) and drop into a pail of soapy water. Crush any eggs that are spotted at this time.
Pesticides- Effective conventional insecticides will contain the active ingredients carbaryl, cyfluthrin, cypermethrin, deltamethrin, lambda-cyhalothrin, permethrin, or zeta-cypermethrin. Organic insecticides containing azadirachtin, pyrethrins, or spinosad can also be used, as well as horticultural oils and insecticidal soap. These control a broad range of pests, including LLB and should be used with caution around other pollinators.
For more information, please visit: https://hort.extension.wisc.edu/articles/lily-leaf-beetle/
