Spatial Emergence Pattern of Bronze Birch Borer, (Coleoptera: Buprestidae) from European White Birch2

Abstract

Spatial emergence patterns of the bronze birch borer, Agrilus anxius Gory, and associated parasite and woodpecker predation in European white birch, Betula pendula Roth, were examined. Beetle and total hole density (beetle + parasite + woodpecker) were significantly lower from stem bolts 6 m above ground, 0.1 to 5.0 cm in circumference, and with 0.1 to 1.5 mm bark thickness than bolts 1 to 3 m above ground, 5.1 to 60.0 cm circumference, and with 1.51 to 3.0 mm bark thickness. Significantly more emergence occurred from the southwestern quadrant of trees than from other quadrants. Beetle emergence and total hole densities were also significantly less from branches than from tree trunks.