Field Crop Insects

Speaker 1: The spring planting season is about a month away. The Iowa Soybean Association and Iowa State University Extension are helping farmers learn about the bugs making their home in Iowa’s fields. Finding the insects might be one thing, but identifying them and the damge they can do is another. CRI reporter John Hoffman brings us more.
John: The recent publication titled “Field Crops Insects” has photos, description and management options for farmers facing an infestation. A few of the common pests that farmers in Mahaska County deal with are aphids, corn borers and corn root worms, to name a few. All are capable of significantly reducing yields. Severe infestation of soybean aphids could result in yield loss of up to 40%. Aphid adults are about one sixteenth of an inch long and feed on the plant’s sap. Aphid activity and feeding is also related to sooty mold. The combination could cause a plant to wilt.

Adult European corn borers are moths about one inch long, but the larvae are what really does the damage and reduces yield. The larvae bore through the stalk and interfere with the plant’s nutrient distribution, and also cause a shot hole effect on the leaves.

There are a couple different types of corn root worms. Corn root worms feed on corn leaves, but they prefer the corn’s silks. The silks that play a very important part in pollination. Not all insects are bad news. Some insects pollinate crops and others feed on those bad news bugs. For example, the pirate bug.

This bug uses a piercing sucking-like mouth part to attack and kill prey like the corn ear worm, the European corn borer, and the potato leafhopper nymphs. Ear worm, corn borer and leafhopper all feed on corn and soybean plants, cause plant damage, and reduce yields. Other insects help with pollination, like the tachinid fly and the flower fly. Both of their larvae feed on other field insects.

If you’re wondering what type of bugs might be a problem for farmers this year, Iowa State University Extensions field agronomist Mark Carlton told me, “farmers won’t know what insects will be a problem until planting begins in the spring. For CRI Weekly News, I’m John Hoffman.
Speaker 1: Thanks, John. The 74 page Field Crop Insects publication is free online at