Content by Adam Varenhorst

Redheaded Flea Beetles Clipping Silks

This week, redheaded flea beetles were observed in corn. Redheaded flea beetles will often strip only a layer of the leaves off corn, which results in windowpane holes, but the bigger issue is that they will also feed on corn silks.

Cicada Killer Wasps Are Active in South Dakota

The cicada killer wasps are active in South Dakota, which means cicadas are probably not far behind. As their name implies, cicada killer wasps use cicadas as a food source. They can present an impressive spectacle if you observe one carrying a paralyzed cicada from a tree.

Small, green teardrop shaped insects on a green, soybean stem with pink flower.

Soybean Aphids Spotted in South Dakota

Soybean aphid populations have been observed in South Dakota. Although these populations are still very small, it is a good reminder that soybean aphid scouting should occur throughout the growing season to prevent population outbreaks and yield loss.

Two beetles. From left: Yellow beetle with a black head and three distinct black stripes on the back. Yellow beetle with a black head and twelve black spots on the back.

Start Scouting for Striped Cucumber Beetles

Striped cucumber beetles are showing up in gardens across South Dakota. If large populations are present in a garden, they can cause severe injury to squash, cucumbers, melons and other cucurbits if left unmanaged.

Three beetles. From left: Black colored blister beetle on a purple flower. Gray colored blister beetle on a green alfalfa stem. Orange-brown colored blister beetle feeding on a sunflower head.

Blister Beetles Showing up in Alfalfa Fields

Blister beetles are now active in South Dakota. Although the larvae of blister beetles can be beneficial by feeding on grasshopper eggs, the adults cause issues when large populations are present in alfalfa at the time of harvest.

Alfalfa plant that has numerous holes in the leaves.

Keep Scouting for Alfalfa Weevils

This week we received a report and picture confirmation of early-instar alfalfa weevil larvae in an alfalfa field. Although most alfalfa fields were treated for alfalfa weevils before the first cutting, those fields still need to be scouted.

Green soybean with wilting/dying soybean within the same row.

Soybean Gall Midge Larvae in South Dakota Soybean

Soybean gall midge larvae were observed in South Dakota soybean this week. Although insecticide applications haven’t been very effective at this stage, it is still important to scout fields and determine the location and extent of soybean gall midge infestations.

Eight green beetles in a row in the top half of the image and a row of seven yellow beetles with varying black stripes in the bottom half of the image.

Corn Rootworm Egg Hatch Estimates

Corn rootworms overwinter in the soil as eggs and hatch in the spring when enough soil degree days have been accumulated. Based on soil degree day accumulations, most of South Dakota has reached 50% corn rootworm egg hatch.

From left: Wheat plants killed by common root rot. Wheat plants with bleached heads due to Take-all disease. Bleached wheat heads due to stem maggot feeding.

Differentiating Between Wheat Head Diseases and Disorders

Several diseases and disorders can develop in wheat heads. Learn the symptoms of several common disease and insect issues being observed in South Dakota wheat this growing season.

A small green corn plant that has been cut and is laying on the ground.

Cut Corn Plants Detected in South Dakota

Cut corn plants have been detected in South Dakota. The damage is due to black cutworm feeding. Although black cutworm caterpillars injure corn by feeding on leaf tissue, the serious damage occurs when caterpillar feeding results in the cutting of young corn plants.