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Insect & Pests

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Left: Black beetle with a red head on soybean leaf. Right: Green soybean leaf with small holes near the center and edges.

Monitor Soybean for Redheaded Flea Beetle Feeding

An additional soybean defoliator to monitor this week is the redheaded flea beetle. Although these beetles are typically not a serious soybean pest, large populations can result in considerable defoliation.

Small white insects with tent like wings present on a green leaf.

What Are These Small White Insects in My Soybean Field?

During the last two weeks we have received reports of increasing numbers of small white insects present on soybean. The insects in question are whiteflies.

: Gray caterpillar with dark markings, white splotches and a white stripe running down the middle of its back.

Monitor Alfalfa for Cutworm Activity

During the spring, there are a lot of insects to scout for in alfalfa. One pest group that should be focused on right now are cutworms. There are a couple of cutworm species that are active earlier in the season than others.

A small black bug with tan margins on the wings. This insect is resting on a blade of grass that is green with white spots.

Be on the Lookout for Black Grass Bugs

It’s time to begin scouting pasture and wheat for the presence of black grass bugs. Last year, we saw the highest populations in areas of Central and Southwestern South Dakota. If left untreated, black grass bug populations tend to increase year after year.

Brown wheat plants that have obvious feeding injury to them due to cutworm caterpillars.

Time to Start Scouting for Cutworms in Winter Wheat

Eventually, South Dakota will warm up. The warmer temperatures will increase insect activity, including pests. For wheat, a couple of early season pests that may already be active are the army cutworm and the pale western cutworm.

Green wheat with many green stink bugs present on it.

Say’s Stinkbug Present in Western S.D. Wheat: Do I Spray?

While looking at winter wheat at the new SDSU West River Research Farm near Sturgis, we came across some very large stinkbug populations in a few areas of the field. The stinkbugs we observed were the Say’s stinkbugs. Although stinkbugs have the potential to reduce wheat yields, this is attributed with feeding that occurs between the late boot and milk stage.

Dark green and tan curled caterpillars with an orange stripe along their sides.

Watch for True Armyworms in Wheat

This week we observed some true armyworm caterpillars in winter wheat fields. The caterpillars were still relatively small, which means they will continue feeding for some time. So far, the true armyworm caterpillars were still feeding on the leaves of the nearly mature wheat, but they have the potential to also clip heads off of the plants.

A small black bug with tan margins on the wings. This insect is resting on a blade of grass that is green with white spots.

Black Grass Bug Activity Expected in Coming Weeks

Spring green-up is the time to be watching for black grass bug activity. Large populations of this early-season pest can cause severe damage to pasture (up to 90% forage reduction) and infest the edges of wheat fields.

Dark colored caterpillar feeding on wheat head.

Scout for True Armyworms in Oats and Wheat

During most years, we start worrying about true armyworm activity in wheat fields in mid-July. However, the strong southerly winds that we experienced during the last two weeks pushed several insect pests north ahead of their normal schedule

Left: Brown moth with light markings present on a green leaf. Right: Brown moth with light markings present.

Army Cutworm Moths Among the Recently Reported Western Bean Cutworm Moths

Last week, we published an article about the presence of western bean cutworm moths being very abundant throughout Central and Western South Dakota. However, when talking with an entomologist from a neighboring state, they suggested the moths could also be army cutworm moths.