Bark Beetle Infestation

June 09, 2013

AshfrassDSCF8508 (2)

Photographer: Curtis McQueen
Summary Authors: Curtis McQueen; Jim Foster

The photo at top shows odd, regularly spaced splotches on the bark of all the ash logs in our woodpile. These appeared in April, a week or two after the white ash wood was cut, split and stacked. At first, we worried that they were the telltale signs of a pest known as the powderpost beetle but how could we be sure? By placing a piece of the firewood in a ziplock bag for several days, I was eventually able to capture several emerging beetles for a definite identification. I went, bag in hand, to our local beetle expert Dr. Greg Setliff at Kutztown University. FrasspileDSCF8514 (2)He took one look and immediately recognized our soil makers as the humble eastern ash bark beetle (Hylesinus aculeatus). We looked at my captured beetles under a microscope and they were identical to specimens in Dr. Setliff's collection all with a distinctive pattern on their backs. These beetles are small, about 1/16 in (2 to 2.5 mm) long.

The splotches on our logs are called frass - chewed bits of wood surrounding the beetles' exit holes. The frass will eventually fall to the ground and become a small but welcome organic addition to the soil mix here at our house. I checked the hole size under one of the frass piles (inset) and found it to be about 1/32 in (1 mm) in diameter. The frass is very powdery and light -- it just blows away with a puff of air. Photo taken in April 2013 from Kempton, Pennsylvania.

Photo details: Top - Camera Maker: FUJIFILM; Camera Model: FinePix S1500; Focal Length: 5.9mm; Aperture: f/2.8; Exposure Time: 0.022 s (1/45); ISO equiv: 400; Software: Digital Camera FinePix S1500 Ver1.03. Bottom - same except: Exposure Time: 0.040 s (1/25); ISO equiv: 800.