One generation of adults matures each year. They gradually make their way close to the surface during the spring, and feed on decaying plant matter and roots. The grubs pupate by May and adults emerge in early July and August. Eggs are laid in soil with decaying vegetation. Like JB, adult GJB are responsible for the principal damage to peaches.
Beetles feed on petioles, leaves and fruit, and a single adult can cause significant damage.
Adults are often found in groups and take large chunks from the fruit. Fruit injury is not as common as that from JB, but does occur when populations are large. Most injury is seen in late July and August, and unlike injury from JB, can occur on both green and ripening fruit. Adults may be monitored by quietly moving into the tree, jarring several branches, and observing how many fly off. Direct fruit counts are the most effective way of assessing damage.