Fully grown larvae are about 1 inch long. Larvae hatch June through July and tunnel into birch tree cambium. They can keep emerging until July. Bronze birch borer larvae are elongate, white, and flattened, with obvious beadlike segments. 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. Adult emergence holes are D-shaped and about 1/8 inch long. A sure sign of bronze birch borer damage is raised bark welts or ridges on the bark, caused by larvae tunneling beneath the bark. Although the life cycle can be completed in 1 year, a 2-year life cycle … The larvae then feed on the phloem and the cambium of the tree and create galleries. Bronze birch borer’s life cycle can last one or two years. Life Cycle: Adults emerge in late May through June. Larvae overwinter and pupate into adult beetles in early spring. Paper and yellow birch are the preferred hosts. Life cycle of the bronze birch borer. Female bronze birch borers lay eggs in crevices and cracks in the birch tree bark. Bronze birch borers attack trees weakened by age, environmental stresses, or previous insect attacks. The bronze birch borer life cycle begins when eggs are laid in branch crotches or bark crevices of host trees. The bronze birch borer (Agrilus anxius) is found throughout the birch range in the U.S. and Canada. The larvae feed through the summer, overwinter as larvae, and pupate in the cambium area in spring. Start to emerge as adults in early June. 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, … Larvae are flat-headed borers with two spines at the posterior end. The larvae excavate tunnels under the tree bark, eating the cambium and phloem until the weather cools in the fall. Welts appear on the surface of the stem above borer galleries (a). Life Cycle. It attacks several species of birch (Betula sp. The eggs then hatch and the small larvae chew through the bark. 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: It takes one to two years to complete development. The adults live for two to five weeks, feeding on leaves, mating and laying eggs in branch or bark crevices. 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. They transform into pupae in spring. There is one generation per year. Females lay eggs primarily on unshaded sides of trunks and branches. 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