Question: What are these white, cottony patches on the leaves of
Hackberry trees? They are floating around and are causing a blackening
on the Hackberry leaves.

Answer: The Asian wooly hackberry aphid, Shivaphis celti, was first
recorded from Florida in 1997 and in south Texas in 2002. But in an
impressive display of this new pest's ability to spread, it has appeared
in large numbers on hackberry trees throughout north Texas this summer.
Entomologists have also reported heavy populations in the upper Texas
Coastal Bend area since July.

The Asian wooly hackberry aphid is only 2 to 2.5 mm-long, and usually
covered with a bluish-white wax. The infestation is obvious on the
undersides of infested leaves, as the aphids resemble small tufts of
cottony wax. They are found exclusively on the leaves of hackberry
trees, Celtis species, including the common, native sugarberry tree.

According to entomologists from the Florida Department of Agriculture,
all adults in the summer are female and produce offspring without
mating. These adults may be winged or wingless. In the fall, winged
males and wingless females mate to produce eggs that can successfully
survive the winter.