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Corn Insects

All Corn Insects Content

Paul O. Johnson making notes about a field of corn

SDSU Extension to Tackle Weed, Pest and Drought Inquiries at State Fair

August 23, 2021

To address drought concerns, as well as weed and pest inquiries, South Dakota State University Extension will feature two booth locations at the 2021 South Dakota State Fair Sept. 2-6 in Huron.

Brown snailcase bagworm cases on the white underside of a jar lid.

Snailcase Bagworms in South Dakota

A unique insect that has been observed in South Dakota is the snailcase bagworm. Snailcase bagworms are wingless moths that spend their entire life in spiral-shaped “snail” cases, which they build around themselves using a combination of silk, soil particles and fecal matter.

Cream mite on a green-colored caterpillar.

Straw Itch Mites

Straw itch mites, also known as hay mites or grain mites, can be a major problem when present in hay or grain. The best way to avoid a straw itch mite infestation is to keep commodities at low moisture levels and bale straw when it is thoroughly dry.

Corn silks with a beetle on them.

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.

Two mites. From left: Green leaf with two yellow spider mites with dark spots. Green leaf with yellow spider mite.

Spider Mites Reported in South Dakota Crops

With drought conditions continuing in South Dakota, it isn’t surprising that two-spotted spider mite infestations are being reported throughout the state. With hot temperatures in the forecast and limited chances for precipitation, we can expect spider mite populations to thrive in infested fields.

Tan grasshopper with light colored stripes on its back sitting on the soil surface.

Grasshoppers Are Causing Concerns in South Dakota Crops

In 2020, grasshopper populations were an issue in parts of central and western South Dakota. The populations this year are moving into crops earlier and appear to be as bad as the ones observed last year.

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.

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.

Tan grasshopper with light colored stripes on its back sitting on the soil surface.

Will Grasshoppers Be an Issue in 2021?

With much of South Dakota experiencing dry conditions this year, grasshoppers are one of the insect pests that will need to be monitored. Large grasshopper populations may cause economic loss in cash crops and reduce forage in range and pasture lands.

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

Common Stalk Borer Activity Estimate: June 10, 2021

The hot temperatures last week have resulted in a large increase in degree days for common stalk borer. Common stalk borers should now be scouted for in areas around Hot Springs, Lemmon, Mission, Pierre, Winner, Huron, Mitchell, Tyndall, Sisseton and Vermillion.