The lily leaf beetle is a close relative of the cereal leaf beetle, another insect that arrived here from Europe and became a major pest. The cereal leaf beetle is no longer a significant problem because we have released three of its natural enemies, and they keep the leaf beetle population within acceptable bounds. The technique of reacquainting a pest with its natural enemies is known as classical biological control. For a generation of gardeners less keen on insecticides than their predecessors, biological control is an exciting alternative. Sayles Livingston of Little Compton, who did her master's dissertation on the lily leaf beetle under Casagrande, is enthusiastic about the project.
Biological control offers hope of a permanent solution to the problem.
Casagrande hopes that the newly introduced wasps will spread throughout the Boston area over the next few years, allowing gardeners to enjoy lilies once again. In the meantime, he and his staff have been rearing and testing three other wasps in a URI lab to determine whether release of a second wasp will improve control of the lily leaf beetle. According to URI research associate Lisa Tewksbury, residents of Massachusetts living near the Rhode Island border have reported heavy infestations of the lily leaf beetle. But to date, the only confirmed sightings in Rhode Island have been in Cumberland. The URI team will establish lily plots there this summer to determine the extent of the lily leaf beetle population.