Campylomma verbasci (Meyer)
by Bradley S. Higbee (firstname.lastname@example.org ), USDA-ARS, Yakima, Wa.
Campylomma is a generalist predator of apple and pear orchard pests including mites, aphids, and pear psylla. Unfortunately it is also recognized as a pest of apple fruit and in rare instances may cause damage to pear. Adults and nymphs are predacious, but may feed on fruit (causing cosmetic damage to skin of fruit) if available prey are reduced to very low numbers. Campylomma occurs in most deciduous fruit growing regions of the northern U.S. and southern Canada.
The adult is green-brown, elongated oval in shape, and about 1/10 inch (2.5mm) long. It has a dark spot on the first antennal segment and black spines on the legs. The nymphs are ovate and translucent when first hatched, but gradually turn pale green. The egg is about 1/28 inch (0.87mm) long and sac-shaped. It is inserted into the bark, stems, and/or leaves of host plants with only the operculum (cap or cover) exposed.
Campylomma is found in both pome fruit trees and herbaceous plants, particularly mullein.
Common prey include aphids, mites, thrips, and pear psylla.
Campylomma overwinters as an egg in apple and pear bark and perhaps other woody deciduous hosts. Eggs hatch in the spring before bloom of apple and pear. Nymphs develop through five instars in about 21 days at 72 degrees F (21 C). The period of nymphal development of the first generation is the time fruit is most likely to be damage by Campylomma feeding. Adults first appear in mid to late May in the Pacific Northwest and a portion of the population moves into surrounding herbaceous hosts, particularly mullein (hence the common name), where they feed on thrips and other available prey. They migrate back into the orchards in late summer, where they mate and lay overwintering eggs. There are from two to four generations per year in the Pacific Northwest.
Campylomma can have a major impact on pear psylla populations in pear and aphid populations in apple. This mirid predator appears to be tolerant to many insecticides and is one of the few predators routinely found in heavily sprayed orchards.
Certain pesticides are known to be highly toxic to Campylomma, chlorpyrifos and formetanate hydrochloride are used when control is necessary, while others may have suppressive or little effect.
Campylomma must be monitored closely early in the season in order to distinguish between beneficial and potentially damaging populations. Although apparently tolerant of many pesticides, use of pesticides that have a narrow spectrum of activity will help conserve this predator.
C. verbasci is not known to be commercially available.
Beers, Elizabeth H., et al.1993. Orchard Pest Management, A resource book for the Pacific Northwest. Good Fruit Grower. Yakima, Wa.
McMullen, R. D., and C. Jong. 1970. The biology and influence of pesticides on Campylomma verbasci (Hemiptera: Miridae). The Canadian Entomologist 102: 1390-94.
Thistlewood, H.M.A. et al. 1990. Seasonal abundance of the mullein plant bug, Campylomma verbasci (Hemiptera: Miridae), on apple and mullein in the Okanagan Valley. The Canadian Entomologist 122: 1045-58.