Nature Nearby: Breaking news! A tree fell in the forest

April 10, 2012

Winds brought down a dead pine on top of Washington Gas’ electronic gas line box near Magruder Park last month. Photo courtesy Fred Seitz.

FRED SEITZ

BY FRED SEITZ — When weekend winds brought down a dead pine on top of Washington Gas’ new electronic gas line box last month, it definitely made a sound, much louder than that of one hand clapping.

The fallen pine, near the Crittenden Street trailhead to Magruder Park, awakened some neighbors and posed a minor obstacle to people traversing the park en route to Metro or other destinations.  A casual glance at the fallen tree revealed evidence of the perpetrators: near-perfect round holes along the trunk are signs of the ribbed pine borer’s modus operandi.

Less than a half-inch long, this tiny villain often attacks and helps kill aging pines that may have been previously weakened by fungi or other fiends lurking in the dark forest.  The mother pine borer lays her eggs on the bark of the potential victim and when her evil offspring hatch, the larvae burrow into the tree and create a small nest (resembling a miniature bird nest) from the wood that they eat.

The nests of pine borer larvae resemble miniature bird nests.  Photo courtesy Fred Seitz.

The nests of pine borer larvae resemble miniature bird nests. Photo courtesy Fred Seitz.

Other parts of the downed pine showed small chambers containing some minute dark material — most likely frass, which is the polite term for beetle poop. The pine borers will pupate into adult form and then exit the tree, seek out a partner to perpetuate their species, and create a lineage of like-minded offenders.

All is not lost to this culture of predators, however. The pines are often policed by nuthatches and chickadees, who devour the small felons in various phases of their nefarious lifestyles.

At the risk of boring readers, this insect is only one of several local boring beetles.  Far more infamous and destructive is the emerald ash borer, an invasive beetle from Asia that has destroyed millions of dollars’ worth of ash trees.

Near-perfect round holes along the trunk are signs of the ribbed pine borer's modus operandi.  Photo courtesy Fred Seitz.

Near-perfect round holes along the trunk are signs of the ribbed pine borer’s modus operandi. Photo courtesy Fred Seitz.

It was introduced into the Detroit area in 2002 in wood packing from Asia, and has rapidly spread through the northeastern states as well as Ontario. The USDA estimates that if unchecked, the beetles could kill up to $60 billion worth of ash trees nationwide.  It has already killed approximately $300 million worth of ash trees in Baltimore. This bright green beetle, which has been spotted in Prince George’s County, has prompted the placement of bright purple traps in ash trees in the county (and

elsewhere in the state) to help the Maryland Department of Agriculture monitor the insect’s spread.  The emerald ash borer has also led to restricted transport of firewood across state lines and, sometimes, in even more localized regions.

Another borer is the bark beetle, who carves elaborate passages in stumps and trees.  This agriculturally minded beetle may actually cultivate fungus in some of their hosts’ chambers, to provide food for larvae. Some artistically minded humans have harvested the highly channeled stumps, applied shellac and used the stump as a decorative item in their homes and/or marketed them at art fairs.

So when we encounter a downed tree or stump, the question can become not only “Did it make a sound?” but also, “Whodunit?”