Skip to main content

Corn Insects

All Corn Insects Content

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.

Seecorn maggot larva feeding on a seed in a field.

Seedcorn Maggot Degree Day Activity Estimates: June 3, 2021

We are currently between the second and third generation peak emergences in South Dakota. Seedcorn maggot management must be done before planting, or the populations can be avoided by not planting during times of peak emergence.

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

Common Stalk Borer Activity Estimate: June 3, 2021

We still haven’t reached the degree day accumulation levels to see common stalk borers moving into corn fields. However, if weeds and grass are sprayed out along field borders, there is a very high probability that they will be forced into corn early.

Green corn leaf with ragged holes through-out caused by common stalk borer feeding.

Common Stalk Borers Observed in South Dakota Corn

While scouting corn this week, clear signs of common stalk borers were observed. Although our degree day estimates indicate that common stalk borers probably aren’t moving into corn yet, they can be forced into corn fields in certain situations.

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

Common Stalk Borer Activity Estimate: May 27, 2021

Throughout South Dakota, we still haven’t accumulated enough degree days for common stalk borers to begin moving into corn, which is a good thing. At this point in time, common stalk borer activity is still going to be limited to weeds and grassy weeds.

Seecorn maggot larva feeding on a seed in a field.

Seedcorn Maggot Degree Day Activity Estimates: May 27, 2021

In South Dakota, we have accumulated enough degree days across the state that the peak emergence of the overwintering seedcorn maggot population has passed. In most of South Dakota, we are at peak emergence of the second generation or slightly past it.

Seecorn maggot larva feeding on a seed in a field.

Seedcorn Maggot Degree Day Activity Estimates: May 20, 2021

Seedcorn maggots can be an early-season pest of corn and soybean in South Dakota, typically affecting crops that are emerging or have recently emerged. Seedcorn maggots can cause direct loss by destroying planted seeds.

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

Common Stalk Borer Activity Estimate: May 13, 2021

The upcoming weather forecast looks warmer than the last few weeks, and that means we will begin to accumulate degree days for the common stalk borer at an increased rate.

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

Common Stalk Borer Activity Estimate: April 29, 2021

As temperatures continue to warm up, degree days are beginning to accumulate a little faster for common stalk borers. Most of South Dakota is still between conditions approaching egg hatch and egg hatch occurring.