What will the predator beetles eat when all the adelgids are gone?
Biological control of HWA by Sasi (or any other predator beetle) has not eliminated adelgids in Asia and is not expected to eliminate HWA in the US. While HWA is their favorite menu item, Sasi will also feed on two other introduced adelgids the Balsam Woolly Adelgid and the Pine Bark Adelgid. By feeding, beetles will reduce the HWA population to a level where it does not damage our hemlocks, establishing a balance between predator beetle and adelgid populations. When the adelgid food supply gets low, then beetle reproduction will decline to maintain a population balance. That is the goal of biological control!
