Hackberry woolly aphids appear as fuzzy, bluish white masses on leaves and other tree parts and are about 1/10 of an inch or less in diameter. Not all the aphids have wings, but those that do have distinct black borders along the forewing veins and their antennae have alternating dark and light bands. As the aphids suck out plant juices, they excrete the sticky honeydew. Sometimes blackish sooty mold grows on the honeydew and creates a sticky mess on leaves and surfaces beneath infested trees.
Before initiating any management methods, inspect hackberry tree leaves for signs of the aphids and make sure they are the culprits of the sticky honeydew and not another insect that also attacks hackberry trees and excretes honeydew: the citricola scale.
For information about other pests and problems on hackberry trees, visit the UC IPM home and landscape web page.