This is not a major pest, but it is often very noticeable when the females cluster on branches, resembling popcorn. Hawthorn mealybug overwinters as a second-instar nymph on the trunks or branches of hawthorn trees, Crataegus spp.
Females lay eggs that are covered with a white waxy covering.
The eggs hatch into nymphs that feed on plant leaves during the summer. They use their piercing sucking mouthparts to remove plant fluids. Heavy infestations of hawthorn mealybug can weaken plants and possibly cause severe defoliation. In addition, this mealybug is a heavy honeydew producer. Honeydew, which is a clear sticky liquid, is an excellent medium for black sooty mold fungi.