The species Campylomma verbasci is commonly known as the Mullein plant bug. This insect is both beneficial and detrimental to Canadian apple orchards. During its early stages of growth the Mullein bug feeds on flowers and developing fruitlets, with the potential of causing serious damage to the growing fruit. However, at maturity, this species feeds on common pests such as aphids, thrips and pear psyllla.
The nymph of the Mullein plant bug is yellow in colour and can reach up to 2.5 mm in length. They have distinct red eyes with a pointed head. The adult is oval in shape with a light green to tan colour. The adult can grow up to approximately 3 mm in length. Damage through feeding during early fruit development results in small, upraised, reddish bumps on the fruit surface.
Damage to fruit occurs with the presence of the nymph stage during bloom up to 2-3 weeks after petal fall. Therefore, scouting should begin during bloom and continue for 2-3 weeks after petal fall, checking 3 times per week. Using tapping trays, sample 25 trees per block and 1 limb per tree, tap each tree a few times to dislodge the insects. A hand held magnify glass may be required to view the nymphs as they are extremely small. Thresholds range from 7-10 nymphs per 25 taps per day of sampling, depending on the species of apple tree. Check your provincial recommendation guide for further details.