Pacific flatheaded borer

You will find reddish-bronze beetles, one-quarter to one-half inch long, on sun-exposed bark of stressed stone fruit trees in May and June. Larvae tunnel beneath bark leaving flat galleries that may girdle branches and trunks. Exit holes and sawdust accumulation appear on affected areas. Young trees and drought-stressed specimens are highly vulnerable. This is a significant pest of orchard and landscape Prunus species.

Plant healthy stock and maintain vigorous growth through proper irrigation and care. Reduce sun-exposure injury on newly planted trees using shade cloth. Remove heavily infested branches below the damage line. Apply preventive sprays in May through July when adult beetles are laying eggs.