June 2, 2008,
Galerucella Beetle damage on Purple Loosestrife Plants
In the fall of 2006, Friends of Fresh Pond Reservation asked the Cambridge Water Department to participate in an effort to control the spread of Purple Loosestrife (Lythrum salicaria, an invasive wetland plant) on the Reservation by releasing Galerucella beetles, that eat only Purple Loosestrife. Last spring the Water Department purchased 5000 Galerucella beetles and released them in the dense stand of Loosestrife that has overrun the wetland at the north end of Little Fresh Pond. We were told that it might be necessary to repeat the procedure for 3 or 4 years until the beetle population became established.
This spring a visit to the wetland revealed a pleasing surprise. Thousands of beetles, the progeny from last year's release, were feasting on most of the sprouting Loosestrife plants.
Left photo: typical "bullet hole" feeding damage by the adult beetles, many of which are visible.
Right photo: Galerucella eggs. When the larvae hatch, they will immediately begin feeding, causing even more damage to the plants.