Insect & Pests

All Insect & Pests Content

Small black and yellow beetle feeding on the green leaf of a canola plant.

Start Scouting Canola for Flea Beetle Activity

There are three species of flea beetles that commonly infest canola and feed on the leaves. The main concern occurs early in the season when these beetles can rapidly defoliate the plants.

Gray beetle with long antennae.

Dectes Stem Borer in Soybean Survey: 2023 and 2024 Results

During the 2023 and 2024 growing seasons, researchers at SDSU surveyed soybean in Eastern South Dakota for the presence of Dectes stem borer adults.

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

Scout Corn for Black Cutworm Activity

Black cutworms are a migratory moth that moves into South Dakota during early spring. Although black cutworm caterpillars cause minor corn injury by feeding on leaf tissue, serious injury occurs when feeding results in the cutting of young corn plants.

Plastic bag containing numerous green larvae.

Alfalfa Weevil Populations Rapidly Increasing in Western South Dakota and Starting to Show up in Eastern South Dakota This Week

Recent degree day accumulations for alfalfa weevils in western South Dakota would suggest that alfalfa weevil larvae activity should be wrapping up for the 2025 season. However, recent scouting of alfalfa suggests otherwise.

Purple-brown caterpillar with orange head on a green corn leaf.

Common Stalk Borer Activity Estimate: May 29, 2025

Based on degree day estimates for common stalk borer caterpillar activity, no scouting in corn fields is necessary at this time.

Green alfalfa weevil larvae with a white stripe running down its body.

Alfalfa Weevil Activity Prediction Update: May 29, 2025

The lowest calculated degree days in South Dakota indicate that fourth instar larvae should be active, while the highest calculated degree days suggest that pupation is occurring in the field.

Red-brown colored weevil with bent antennae originating on the elongated mouthparts.

Red Sunflower Seed Weevils in South Dakota

Fact sheet on red sunflower seed weevils in South Dakota

A yellow beetle with a black head, and square black markings on its back standing on a soybean leaf.

South Dakota Overwintering Bean Leaf Beetle Predicted Mortality: 2024-2025

Each year we evaluate the overwintering success of bean leaf beetles in South Dakota. For adult bean leaf beetles that successfully overwintered, emergence will begin in the spring and they will move into soybean fields.

Alfalfa weevil larvae and adult.

Alfalfa Weevils Are Active in Some Parts of South Dakota

Degree day accumulations indicate that alfalfa weevil larvae should be active throughout South Dakota.

Green alfalfa weevil larvae with a white stripe running down its body.

Alfalfa Weevil Activity Prediction Update: May 22, 2025

Degree day accumulations for alfalfa weevil larvae indicate that third to fourth instar larvae should be active in fields throughout South Dakota.