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The following is a letter from Donna Ellis, senior extension educator and co-chair of the Connecticut Invasive Plant Working Group at the University of Connecticut in the Department of Plant Science and Landscape Architecture.
I worked with New Canaan Nature Center staff, beginning with Ann Harper and Vinnie Piselli in 1998, to introduce beneficial insects for purple loosestrife control. We introduced Galerucella beetles and Nanophyes weevils in two of the wetland areas at the center. It took approximately five years before we observed significant feeding damage. In 2008, Piselli reported that all purple loosestrife plants on the property were heavily damaged by the Galerucella beetles and very stunted. Piselli estimated that in 1998 there were 7 acres of meadows and wetlands with more than 70 percent purple loosestrife infestation levels. In 2008, he estimated that plant populations were reduced to 20 percent at all sites.
I have visited the New Canaan Nature Center every one to two years since the initial releases, and my last visit was Aug. 18, 2010. I noticed during my visit last year that purple loosestrife was abundant and in full bloom. But upon closer inspection, many plants showed signs of earlier feeding damage on the leaves (when leaves are inspected mid-canopy there were many feeding holes from the beetles), with terminal shoots destroyed and a lot of lateral growth occurring, making the plants appear shorter and more bushy. Galerucella beetles are only active from May through mid-July, after which time adult beetles move underground and remain inactive until the following May.
I coordinate the Purple Loosestrife Beetle Farmer Program in the state, where volunteers receive training to rear and release Galerucella beetles in wetlands where purple loosestrife is a concern. Since the program began at the University of Connecticut in 1996, more than 725 beetle farmers have been trained in this program and together we released 1.8 million Galerucella beetles in more than 100 wetlands throughout the state. It is possible that the beetles have dispersed to other wetlands in New Canaan, or their numbers have decreased with time. Perhaps next year the Nature Center could encourage volunteers to release additional beetles to supplement the control that is under way.
For more information, visit the Connecticut Purple Loosestrife Program website at www.purpleloosestrife.uconn.edu.
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