9 bugs to keep an eye on this year

  • 01

    Here are 9 insect pests that could cause row crop farmers headaches this year, says Cropsey, Illinois, crop consultant and farmer Aaron Steffen. "The mild winter will contribute greatly to the insect population for 2012," Steffen says. "We are set up for one Big Buggy Year." Always check with your your agronomist or crop specialist for more specific guidance on insect pressures specifically in your fields.

  • 02


    Wireworms and adult click beetles damage cereal and forage crops, including corn. Look for a shiny yellow or brown worm 1/2 inch to 1 1/2 inches long. Adult click beetles lay tiny white, round eggs in the soil and wireworms feed on corn germ or kernels, leaving them hollow. Sampling can be done either before or after planting; wireworms are usually found in the top 6 inches of the soil.

  • 03

    White grub

    There are several types of white grubs in the Midwest that grow into Japanese beetles, Masked chafers and May/June beetles. The small grubs thrive in corn fields that were previously in sod or a cover crop, feed on corn seedlings, leaving them stunted, wilted or discolored. Start scouting first in each field in 5 random areas, digging 6 inches deep in each 2x1-foot space.

  • 04

    Stink bug

    The green stink bug typically thrives on wild plants, but can easily move over to soybeans. Scout for this green, shield-shaped bug on soybean pods, which the bug punctures and removes fluid. Damaged pods prematurely harden and drop or become shriveled or discolored. Use a sweep net in 5 areas of your soybean fields, including field borders, to get a sense of stink bug numbers.

  • 05

    Black cutworm

    The moths are common in the Midwest. The gray/black larvae have a greasy feel and grow up to 2 inches in length. They're worst in fields where weeds or other plants precede corn planting, and most damage comes in leaf feeding and notching in young corn stems right below the soil surface. Pheromone traps are best for detecting black cutworm populations.

  • 06

    Seed corn maggot

    This pest is common in no-till fields or those with heavy amounts of crop residue, where it thrives in damp, cool springs. Look for a pale, white maggot 1/4 inch long in the seed kernel. The maggots can feed up to 3 weeks (causing some seeds to never emerge) before pupating in the soil. Scouting best starts in areas of corn fields with spotty emergence.

  • 07


    Maize billbugs, reddish-brown in color and up to 1/2 inch long, are active at night. They overwinter in soils with coarse grass or plant litter material and start feeding at emergence. They feed and lay eggs at the soil level, and damage with small holes in the stem, which can kill some plants if around the growing point. To scout, check 20 corn plants in 5 locations.

  • 08

    Flea beetle

    This tiny (usually around the size of the head of a pin), black bug deposits its eggs on weeds, corn and other row crops in the soil near host plants. Larvae feed on roots, pupate in the soil then emerge and commence leaf-feeding usually around mid-summer. Scouting for this bug is similar to Billbugs -- check 20 plants in 5 random spots in the field.

  • 09

    Soybean aphid

    Soybean aphids aren't much bigger than Flea beetles, but can cause major damage. This bug, green in color, overwinters on buckthorn and can produce offspring several times during the summer, creating season-long pressure in some cases. They use needle-like mouths to withdraw moisture from soybean leaves. Scout 20-30 plants per field; the economic threshold for treatment is around 250 bugs/plant.

  • 10

    Bean leaf beetle

    This bug, which can be yellow, tan or red and around 1/4 inch in length, hammer soybean leaves and pods. They can start causing damage early, first feeding on stems and cotyledons. It's best to scout bean leaf beetles early, at mid-season and toward the season's end. Check stems first, then look for defoliation, then pod damage late in the year.

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