BENEFICIAL INSECTS & MITES

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Many other insects, spiders, predators and parasitoids are often found in mint fields. Most of these other animals are not pests and may be either predators or parasites of pests. All beneficial insects and mites should be conserved by using insecticides only when necessary to control a pest that has exceeded the treatment threshold.

Predators effectively control many small, soft-bodied pests such as aphids, mites, small worms, and insect eggs. The most commonly found predators include:

LADY BEETLE ADULTS {bmc ldbgai.bmp} are about 4mm long, oval and convex in shape, reddish-orange or black, usually with spots on the winds. LARVAE {bmc ldbgli.bmp} are gray or bluish-grey, with numerous yellow, white, or red spots (Figs. 25, 26 PNW Pub. #182).

SYRPHID FLY LARVAE {bmc syrphli.bmp} (Fig. 28 PNW Pub. #182) are about 12 mm long, wrinkled or slug-like in appearance,tapering to a point at the head. GREEN LACEWING ADULTS {bmc lcwgai.bmp} are green to yellowish-green with four, delicate transparent wings with many veins and crossveins. LARVAE {bmc lcwgli.bmp} are slender, mottled gray or yellowish-gray and about 9.5 mm long (Figs. 29, 30 PNW Pub. #182).

BIGEYED BUG ADULTS {bmc miridi.bmp} are about 3 to 6 mm long, buff gray or blackish in color with large, prominent eyes. Nymphs resemble adults except in size and absence of wings (Fig. 33 PNW Pub. #182).

MINUTE PIRATE BUG ADULTS {bmc minpi.bmp} are oval-shaped, about 3 mm long, very flat, and marked conspiciously with black and white. Nymphs and adults have piercing-sucking mouthparts enclosed in a long beak (Fig. 34 PNW Pub. #182).

DAMSEL BUG ADULTS are tan or gray, with piercing-sucking mouthparts and enlarged front legs for grasping their prey. They have slender bodies, and are 10-12 mm long. NYMPHS {bmc damai.bmp} resemble adults, except they are smaller and have no wings (Fig. 35 PNW Pub. #182).

SPIDERS are important but often overlooked predators in peppermint. They feed on most insects especially in the younger stages. A list of the spiders found in peppermint has been compiled (McIver and Belnavis, 1986).

BIRDS are frequent predators of cutworms and loopers, especially as the insects reach the middle and later larval stages.

In some areas, BATS can be important predators of flying insects, including cutworms and loopers.

PREDATOR MITES {bmc predmi.bmp} are similar to the twospotted spider mite in size, 0.25 to 0.5 mm, but are more flattened and lack spots (Fig. 36 PNW Pub. #182).

PARASITES (also known as parasitoids) are important in the control of many cutworm and looper larvae, particularly variegated cutworm and the loopers. Most are tiny wasps which are easily over-looked. However, they play an important role in controlling insect pests in mint. In most instances, larvae that have been parasitized die before causing significant plant injury. Parasites are either Hymenoptera wasps {bmc ichai.bmp} (Figs. 31, 32 PNW Pub. #182) or Diptera flies, which resemble common house flies.

PARASITIC NEMATODES {bmc nemai.bmp} are tiny parasites that enter soft- bodied insects and release a symbiotic bacterium that reproduces and kills the host (Fig. 37 PNW Pub. #182). They control soil pests in mint: mint root borer, strawberry root weevil, and mint flea beetle.