Sunday, August 9, 2015

Beech Blight Aphids

     On the most recent Wildflower Walk at Bell Smith Springs we stumbled upon a furry white insect on the twigs of a beech tree, with a few spilling over on the leaves.  I refer to them as boogie woogie bugs, but they are more commonly known as beech blight aphids (Grylloprociphilus imbricator). Whatever you call them, these aphids are a species of true bugs. belonging to the order Hemiptera and the family Aphididae.
Beech Blight Aphids (Grylloprociphilus imbricator)
     The white waxy filaments are secreted by the aphids and make them unappealing to prey.  They wave their bodies around, fanning the cotton-like tufts when they are disturbed, reminding predators not to bother them.  These fascinating insects feed on the sap of the beech trees, but do not cause any major lasting damage to them.  The aphids are particularly interested in the protein contained in the plant sap.  Yet most of the plant sap is water and carbohydrates, basically sugary water, As they pierce the branch with their specialized mouthparts, the high pressure of the liquid in the vascular tissue causes sap to shoot out of the tree and into the insect, in this case, the aphid.  This causes the previously ingested watery, sugary sap to shoot quickly through the digestive tract and out of the body of the aphid.  The resulting liquid is called honeydew, or one could think of it as aphid excrement.
     Nature has a way of letting nothing go to waste.  One organism's waste is another's treasure.  And such it is with the aphid poop.  It attracts a black mold called the beech blight sooty mold (Scolias spongiosa).  This mold is a specialist, as it only grows on the honeydew of the beech blight aphid.  This species of aphid likes to congregate, which concentrates the honeydew.  This is why the black sooty mold grows in large clumps, versus other black mold, which is restricted to just a light layer on the leaves because of solitary aphid species.   
     Yet another example of how nature is amazing.  Watch a short video here.

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