Index

Stink bug: late season pest of concern

Life cycle

Monitoring

Control

Fruit injury

Figure 1. Green stink bug Acrosternum hilare

Figure 3. Stink bug life cycle

Stink bugs overwinter as adults and become active in the spring (Fig. 3). Adult stink bugs lay eggs on a wide variety of native shrubs, including wild rose, red osier dogwood, bitterbrush, and wild currents and some

perennial weeds, such as mullein, mallow, and white clover. Nymphs feed on these native plants, and mature to adults in mid-July. While some injury to sweet cherry has been attributed to early season feeding by overwintered stink bug, most injury to apple and cherry occurs in mid to late summer when new adults move into the orchard from outside habitats. Visit Orchard Pest Management (OPM) online at jenny.tfrec.wsu.edu/opm for more information on stink bugs and their behavior.

Figure 4. Red-shouldered stink bug Thyanta accerra

Recently, high populations of two stink bug species (Chlorochroa and consperse) have been reported attacking late maturing sweet cherry (Fig. 5) and are now beginning to move into apple

orchards. It can be difficult to determine when stink bugs begin moving into orchards because they areprimarily active at night and hide during the day when they detect movement. Pyramid traps (Fig. 6) and commercial lures can be used to monitor the consperse stink bug. Traps may also be effective in detecting adult Chlorochroa but the availability of a commercial lure is unknown.

Figure 6. Pyramid traps used to monitor stink bug movement.

Managing stink bug populations can be difficult because they spend much of the year living on host plants outside of the orchard. Adult stink bugs may move into the orchard in late summer and feed on fruit, both apples and cherries. When stink bugs are detected within the orchard, the only effective means of protecting a crop is to apply contact insecticides. Pyrethroid insecticides have proven to be the most effective insecticide options for control of stink bugs, but even a single application

can be highly disruptive to biological control of spider mites and other insects. To limit the disruptive effects, targeted sprays of orchard borders are recommended. Repeated applications of a pyrethroid insecticide to orchard borders, 4 to 5 rows, has worked well to reduce fruit injury in the entire orchard. Sprays are most effective when applied at, or shortly after, dusk - the period of highest stink bug activity. Some pyrethroid insecticides have labels for non-crop lands and

Damage caused by stink bugs can be confused with bitter pit damage. Stink bug damage (Fig. 9) is usually located higher on the fruit, is conical or rectangular in shape, and ranges from very light tan to dark brown in color. Bitter

Figure 10. Wedge cut apple reveals bitter pit disorder.

pit damage (Fig. 10) is distributed on the sides of the apple and near the calyx, is spherical in shape, and usually dark brown to black in color.