Scorias spongiosa

Scientific name: Scorias spongiosa (Schwein.) Fr. 
Derivation of name: Scor means "dung" or "excrement"
perhaps in reference to its overall appearance or to the fact
that the fungus "eats" the excrement of the beech blight
aphid; spongiosa means "spongy."  
Synonyms: Botrytis spongiosa Schwein.  
Common name(s): Honeydew eater, black sooty mold 
Phylum:   Ascomycota
Order:   Capnodiales
Family:   Capnodiaceae
Occurrence on wood substrate: Saprobic; occurs on twigs,
branches, leaves, and bark of American beech (Fagus
grandifolia); summer through fall. 
Dimensions: Sponge-like agglomerations of black hyphae
may reach diameters of 15 cm when growing on twigs and
branches, larger if at the base of the trunk.
Description: Scorias spongiosa does not grow on the
wood of American beech. Rather, it feeds exclusively on
the honeydew (excrement) of beech blight aphids
(Grylloprociphilus imbricator) which feed exclusively on
American beech. The copious honeydew produced by heavy
aphid infestations falls onto twigs and branches below the
infestation and there supports the growth of the fungus. The
initial growth is straw-colored and as the mycelial mass ages,
it darkens and becomes black. Hyphae stick together to form
mycelial strands which can project away from the structure,
giving it a rough, sponge-like appearance. The end result is
black, conspicuous, sponge-like masses on the twigs,
branches and bark of beech trees.     
Comments: Scorias spongiosa is a sooty mold fungus, one of
many sooty mold fungi. Whereas other sooty mold fungi form
thin, dark layers on the surface of leaves on which aphid
honeydew has dripped, the abundant beech blight aphid
honeydew is able to support extensive masses of Scorias
spongiosa. The posteriors of beech blight aphids are covered
with long, white, waxy filaments. Heavy infestations may give
the appearance that infested twigs and branches are covered
with snow. When threatened, the aphids lift their posteriors
and sway them from side to side giving rise to the name
"Boogie-Woogie aphid."  

More Information at Wikipedia.org

Figure 1. American beech with a mass of Scorias spongiosa on
a twig. Photo © Gary Emberger.


Figure 2. Closer view of the black sooty mold mass in Figure 1.
Photo © Gary Emberger.

Figure 3. The agglomeration of black hyphal strands, some of
which project away from the mass, gives the entire structure
a rough, sponge-like appearance.
Photo © Gary Emberger.

Figure 4. This twig, supporting less of the sooty mold fungus,
was below the twig in Figure 3. Photo © Gary Emberger.

Figure 5. A spider perched on the mass of Scorias spongiosa.
Photo © Gary Emberger.