Distinguishing nymphal stages of apple pests. Both nymphs and adults are fast moving, and adults are often quick to take flight is disturbed. There are 2 to 3 generations per year. The mullein bug has two major plant hosts, the mullein plant and apple. Occasionally it will also attack pear, grape, wild rose, serviceberry and oak.
Nymphs begin hatching during bloom and continue to hatch into the petal fall period.
Most years the hatch is very synchronized with peak emergence at early petal fall. However, a cold snap during this time may result in split hatch, making chemical control more difficult. Nymphs will initially feed on plant sap attained from leaf veins, but will also sting developing fruitlets. Several weeks after petal fall the nymphs become predaceous and begin feeding on small prey such as European red mite and aphids. Nymphs with red bellies are an indication that they have been feeding on mites.