Oviposition site preferences for Galerucella calmariensis and G. pusilla, biological weed control agents against purple loosestrife, were examined in 1994 and 1995. The leaves, stems, axils, and flower buds (G. pusilla did not oviposit on flower buds) were found to be the preferred oviposition sites. Oviposited egg masses may be used as a parameter within a biological control monitoring plan, providing information on Galerucella establishment and/or presence, estimating future population size, and providing biological control agent dispersal information. Monitoring for egg masses should concentrate on host plant leaves, where over 56% of all egg masses were oviposited.
