Three beetle species have been grown and released in Illinois since 1994. Two of these species feed as both adults and immature larvae on the leaves and growing tips. They have one generation per year and overwinter as adults. Eggs are laid in clusters of 5-20 on the leaf surface, often where the leaf joins the stem. The feeding causes holes in the leaves, reducing the amount of leaf area, weakening the plant.
Adults live for several years.
Root feeding is extensive enough to kill the plant. Approximately 1,000 eggs of Hylobius have been released at about 20 sites. Before the insects were allowed into the U.S. in the early 1990s, they were tested against 49 species of plants to determine on which ones what they would feed. This was done by looking first at the closest relatives, then more-distantly related species including many of our important agricultural crops. With the Hylobius weevils, a few laid eggs on winged loosestrife and swamp loosestrife, but larvae developed completely only on swamp loosestrife.