Species Agrilus anxius - Bronze Birch Borer

Agrilus anxius Gory 1841

♀ 7.7-11.3 mm, ♂ 6.5-9.8 mm(1)

throughout the range of birches (most of Canada + the US south to AZ-NM, FL)(1)(2)

on most birch species(3), and cottonwoods(2)

Adults emerge in late May or early June and depending on location, can continue emerging until August. They feed on leaves for about 3 weeks then lay their eggs single or in small groups beneath loose flakes or bark, cracks, or crevices in unshaded parts of the tree.(4)

Young larvae bore thru to the cambium. They excavate galleries between the bark and the wood with occasional side trips into the xylem to molt and then to spend the winter. The galleries wind back and forth, usually across the grain. Mature larvae construct oblong cell in the thick bark where the spend the winter and pupate in the spring.(4)

2 generations per year in the North; one in the South.(4)

Fact sheets by G.A. Hoover, by D.J. Shetlar(3)