The Woolly Hackberry Aphids are small, sap-sucking insects. Large infestations of woolly hackberry aphids can look like "snow" falling from hackberry trees or small pieces of cotton floating in the wind. Feeding damage can weaken plants due to the loss of sap and cause stippling on leaves. Infestations are sometimes first noticed by the presence of black sooty mold on the leaves, bark, and area under a plant. This is due to the large amount of honeydew, or excrement, from aphids which supports the growth of sooty mold fungi. Although sooty mold does not damage the plant directly, heavy accumulations of sooty mold are unsightly and interfere with photosynthesis.