Hawthorn Mealybug – Two-Circuli Mealybug – Phenacoccus dearnessi

Hawthorn Mealybug/Two-Circuli Mealybug (Phenacoccus dearnessi)

Common Name: Hawthorn Mealybug – Two-Circuli Mealybug

Latin Name: Phenacoccus dearnessi


  • Later stages of the insects are visible on the twigs, rounded in shape and coated with a crimson body that is beautifully covered with white wax.
  • During the winter, small but more elongate pale reddish-brown juvenile forms can be observed on the bark of the trunk and bigger branches.
  • Adult males are little, gnat-like flying insects that migrate from branches to twigs in the spring.

Host plant:

Several rosaceous species are known as hosts, including hawthorn, mountain ash, and serviceberry.


The hawthorn mealybug is a non-native species with little potential to spread. Some, but not all, landscape plantings of sensitive hawthorn include it. It has not been found in natural hawthorn stands.

Damages caused by Two-Circuli Mealybug:

The sap of twigs and small branches is the principal food supply for the hawthorn mealybug, and large infestations weaken the plant and induce twig dieback. The large amounts of honeydew cause the most common problems it excretes when consuming. Sooty mould and honeydew are common and can greatly detract from plant appearance.

Life history and habits:

The hawthorn mealybug spends the winter as a second-instar nymph on the trunks or branches of Crataegus spp. Hawthorn trees. Females, approximately 1/8 inch long, disseminate to the base of buds in the spring. Females deposit eggs that have a white waxy coating. During the summer, the eggs hatch into nymphs and graze on plant leaves. They extract plant juices using their piercing-sucking mouthparts. Hawthorn mealybug infestations can weaken plants and cause significant defoliation. This mealybug also produces a lot of honeydew. Honeydew, a transparent sticky liquid, is an ideal habitat for black sooty mould fungus. Nymphs move to return to the trunk and branches of hawthorn trees to overwinter in the fall.