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Other Predatory Bugs

Other kinds of predaceous bugs are often found in beating tray samples throughout the year. As a group, they prey on most tree fruit pests. Alone, they are rarely numerous enough to provide effective biological control of pests, but collectively they can have an important impact.

Bigeyed bugs

Geocoris spp. (Hemiptera: Lygaeidae)

Bigeyed bug (Geocoris sp) adult feeding on lygus nymph (D. Mayer)

Bigeyed bugs prey on lygus bugs, aphids, leafhoppers and spider mites. Both adults and nymphs feed by sucking body fluids from their prey. They are most commonly found on alfalfa but occur in fruit trees when abundant in the orchard cover crop. The adult is dark gray or black and about 1/8 to 1/4 inch (3 to 6 mm) long, with prominent eyes. The nymph is similar but is smaller and lacks wings. Bigeyed bugs overwinter as adults in litter or other protected areas on the ground. Adults appear in spring. Females deposit eggs, which are ribbed and pink or pale yellow, in plant tissues. Nymphs feed on prey for several weeks before maturing. There are usually two generations each year.

Damsel bugs

Nabis spp. (Hemiptera: Nabidae)

Damsel bugs (also called nabids) prey on aphids, lygus bug nymphs, leafhoppers, scales, mites, and the eggs and larvae of moths. They also prey on other natural enemies.

Damsel bug adult (J. Brunner)

The adult is tan or gray with piercing-sucking mouthparts and enlarged front legs for grasping its prey. It has a slender body, tapering at the rear, and is about 3/8 to 1/2 inch (10 to 12 mm) long. The nymph is similar to the adult but is smaller and lacks wings. Damsel bugs are often found in large numbers on the cover crop and will occasionally climb trees and prey on fruit pests. Although they are swift and aggressive, their feeding rate is fairly low. They can play an important role in biological control of tree fruit pests because they appear in the orchard as early as March and occasionally are abundant throughout the summer. They overwinter as adults in weeds, grain or alfalfa fields. Adults begin laying eggs soon after emerging in the spring. Eggs are flat on top and are deposited in soft plant tissue. There are 3 or 4 overlapping generations each year in the Northwest.

Assassin bugs

(Hemiptera: Reduviidae)

Assassin bug adult (J. Brunner)

Assassin bugs are fairly large brown to black bugs. Nymphs and adults prey on aphids, leafhoppers and caterpillars. They are not selective predators and will feed on other predators such as lady beetle larvae.

Assassin bugs are characterized by a long, narrow head and a stout, conspicuous beak, which is used to attack its prey. The “wheel bug” is one of the assassin bugs, characterized by a toothed hemispherical appendage on the top of the prothorax.

Rough plant bugs

Brochymena spp. (Hemiptera: Pentatomidae)

Rough shield bug (Brochymena sp.) (E. Miliczky)

Although many stink bug species are pests, those of the genus Brochymena are predaceous as both nymphs and adults. Predaceous stink bugs are most often found on forest trees and shrubs but also occur on fruit trees, where they prey on caterpillars, beetles, pear psylla, aphids and other insects. They puncture the prey with their stylets (mouthparts) and suck out the juices. Eggs are pearly white, oval and about 1/25 inch (1 mm) long and are laid on twigs or leaves in small groups. Both the nymph and adult are a steely gray with white specks. The coloring distinguishes the predaceous species from the consperse stink bug, an orchard pest, which has black specks. The adult is about 1/2 inch (12 to 15 mm) long. Brochymena has one generation each year and overwinters as an adult.

Washington State University