What’s in the Woods Today? September 20, 2018

by Area Forester Lisa Deaton

Boogie Woogie Aphids

Near the end of August, beech blight aphids, Grylloprociphilus imbricator, appear on American beech trees.  They are easiest to find by locating patches of black sooty mold on the ground underneath infested beech trees.

sooty mold lo res

In the photo above, the orange fungus on the right was the first thing I noticed.  Once I saw the sooty mold to the left, I looked up, and voilà, a branch full of wooly-looking aphids!

single branch snow

These are always a surprise to see during the heat of summer because they look so much like snow.

The fun part of encountering these aphids is waving your hand over the top of the branch and watching them wave their bodies back and forth in an effort to scare off predators.  That is how they earned the common name of boogie-woogie aphids.  You can see them do the boogie woogie in this video:

Like many sap-sucking insects, beech blight aphids take in more sugar than they need, and excrete the excess as honeydew.  The black sooty mold grows on any surfaces covered with honeydew, such as the base of the tree below.

tree trunk

The aphids and mold do very little harm to their host beech trees.  On pages 15-16 of our January 2013 issue of Forest Health Review, forest health specialist Chris Asaro explains all of the intricate relationships between the aphids, trees, ants, and different molds produced.

Now is a great time to explore nearby woods and look for colonies of boogie woogie aphids on American beech trees.  They seem to be present in great numbers in Gloucester County this year.

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