The adults (beetles) emerge from pupation under the bark of the host tree from May to mid-July, depending on climatic conditions. The eggs hatch about 14 days later. As the weather warms in spring, the larvae resume feeding. Biology and life history The insect overwinters as a larva in the tree. The larvae remain in these galleries through winter until they pupate in spring. Life Cycle: It takes one to two years to complete development. Although the life cycle can be completed in 1 year, a 2-year life cycle … The adults live for two to five weeks, feeding on leaves, mating and laying eggs in branch or bark crevices. Bronze birch borers live through the winter as larvae under the bark of trees in pupal chambers. Paper and yellow birch are the preferred hosts. The larvae then feed on the phloem and the cambium of the tree and create galleries. The larvae excavate tunnels under the tree bark, eating the cambium and phloem until the weather cools in the fall. They transform into pupae in spring. ), but is especially devastating on exotic birch species including European white birch (Betula pendula). Life cycle of the bronze birch borer. The eggs then hatch and the small larvae chew through the bark. Larvae hatch June through July and tunnel into birch tree cambium. Bronze Birch Borer (Agrilus anxius) is a North American insect pest that has damaged and killed tens of thousands of birch trees in Canadian landscapes. Life Cycle: Adults emerge in late May through June. Adult emergence holes are D-shaped and about 1/8 inch long. Bronze birch borer’s life cycle can last one or two years. A sure sign of bronze birch borer damage is raised bark welts or ridges on the bark, caused by larvae tunneling beneath the bark. They can keep emerging until July. Larvae overwinter and pupate into adult beetles in early spring. Adults are dark green-bronze or copper-bronze and about 3/8 inch long. Bronze birch borer larvae are elongate, white, and flattened, with obvious beadlike segments. Bronze birch borers attack trees weakened by age, environmental stresses, or previous insect attacks. Welts appear on the surface of the stem above borer galleries (a). The life cycle of bronze birch borer can be annual or biennial depending on climate and host condition, with 2-yr life cycles more prevalent in cooler climates and on more vigorous hosts (Slingerland 1906, Balch and Prebble 1940, Anderson 1944, … Life Cycle. The bronze birch borer life cycle begins when eggs are laid in branch crotches or bark crevices of host trees. Fully grown larvae are about 1 inch long. Females lay eggs primarily on unshaded sides of trunks and branches. Start to emerge as adults in early June. Larvae are flat-headed borers with two spines at the posterior end. Bronze Birch Borer. The bronze birch borer (Agrilus anxius) is found throughout the birch range in the U.S. and Canada. It attacks and breeds in paper birch, yellow birch, gray birch, western birch, water birch, and sweet birch, and has been found in stands of beech and aspen. Female bronze birch borers lay eggs in crevices and cracks in the birch tree bark. It attacks several species of birch (Betula sp. The larvae feed through the summer, overwinter as larvae, and pupate in the cambium area in spring. The first symptom of a bronze birch borer problem is often yellow, sparse, stunted leaves in the upper portions of the tree which may progress to twig and branch dieback if larval populations are high. There is one generation per year.