ADDITIONAL INFORMATION ON IDENTIFICATION OF MAJOR MINT PESTS CAN BE FOUND IN PNW BULLETIN No. 182 IN THE BACK OF THE IPMP MANUAL. IF YOU NEED ASSISTANCE TO IDENTIFY INSECTS ON MINT, SEND SPECIMENS TO THE INSECT DIAGNOSTIC LABORATORY, DEPARTMENT OF ENTOMOLOGY, CORDLEY HALL RM 2046, OREGON STATE UNIVERSTY., CORVALLIS, OR 97331-2907.
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INSECTS FEEDING ON MINT LEAVES
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1. Plants cut-off slightly below or above the soil surface; leaves with ragged- edged holes and above ground stems with notches eaten out. CUTWORMS such as: VARIEGATED CUTWORM {bmc larvai.bmp}(Figs. 3, 4 PNW Pub. #182), SPOTTED CUTWORM{bmc larvai.bmp} (Fig. 5 PNW PUB. #182), BERTHA ARMYWORM, WESTERN YELLOWSTRIPED ARMYWORM {bmc larvai.bmp} (Fig. 6 PNW Pub. #182), REDBACKED CUTWORM {bmc larvai.bmp} (Figs. 1, 2 PNW Pub #182), and BLACK CUTWORM. Damage from redbacked cutworm and black cutworm usually occurs in April, May, and June. Other cutworms typically cause injury in July and August.
2. Ragged-edged holes eaten through the leaves and around the leaf margins particularly on leaves mid-way and higher on the plants. LOOPERS including: ALFALFA LOOPER {bmc larvai.bmp} AND CABBAGE LOOPER (Figs. 7, 8, PNW Pub #182).
3. Terminal leaves and buds tied together with silk. Upper surfaces of leaves skeletonized or with small holes. FALSE CELERY LEAFTIER {bmc larvai.bmp} (pg. 5, PNW Pub. #322 and (Figs. 17, 18, PNW Pub. #182)
4. Ragged or completely eaten leaves present on plants around the field margins at first, later entire field with a ragged appearance. GRASSHOPPERS {bmc ghi.bmp} (Fig. 22 PNW Pub #182).
5. Small semicircular holes or irregularly shaped notches chewed in the leaf margins. STRAWBERRY ROOT WEEVIL ADULTS {bmc srwi.bmp} (Fig. 14 PNW Pub #182).
6. Very small holes in leaves giving a shot-hole appearance to the leaves. MINT FLEA BEETLE ADULTS {bmc mfbai.bmp} (Fig 12 PNW Pub #182).
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SUCKING INSECTS ON LEAVES OR STEMS
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1. Feeding injury caused by small and soft-bodied insects often found in large numbers on the undersides of the leaves and along the stems. Feeding may cause stunting, discoloration and leaf curling. Leaves often covered with sticky substance (honeydew) and black sooty mold growing on honeydew. MINT APHID {bmc aphidi.bmp} (Fig. 24 PNW Pub. #182).
2. Feeding injury caused by small, soft-bodied animals with eight legs visible under 15X magnification. Large numbers found on the underside of leaves. Leaves may have webbing on the undersides. Feeding causes speckled appearance on the leaves. Leaves may turn brown or bronze and drop from the plant, particularly late in the growing season. TWOSPOTTED SPIDER MITE {bmc mitei.bmp} (Fig. 23 PNW Pub. #182). Predator mites also may be present on the leaves (Fig. 36 PNW Pub. #182).