Beneficial Insects in Corn

December 1, 2025

Not all insects found in corn are pests. In fact, relatively few of the insects found in corn are pests. Most insect species found in corn are beneficial and are classified into three broad groups: predators, parasitoids, and pollinators. Examples of predators are lady beetles, ground beetles, assassin bugs, green lacewings, syrphid flies, wasps, and although not insects, spiders. I am going to focus on three very common predators, lady beetles, ground beetles, and green lacewings.

Lady Beetle

These are the most recognized predatory insect. They are oval, relatively small, and can range in color from yellow, red, orange and even black (Figure 1). The wing covers are usually spotted. Both the adult and larvae are predatory, with the larvae (Figure 2) often referred to as aphid dragons. Aphids are a favorite food for adults and larvae. It has been estimated that a single lady beetle consumes 5,000 aphids in its life.1

Adult lady beetle. Picture courtesy of Frank Peairs, Colorado State University. Bugwood.org.


Lady Beetle (Bug) Larva image
Figure 2. Lady beetle larva. Picture courtesy of Frank Peairs, Colorado State University. Bugwood.org.

Ground Beetle

Ground beetle larvae are predators that feed on soil-dwelling insects and other soil inhabitants (Figure 3). Pests fed upon may include the eggs and larvae of pests such as aphids, mites, mealybugs, caterpillars, grubs, fly maggots and pupae, root maggot larvae in the soil, and other small soil dwellers such as snails and slugs. Some ground beetles also consume weed seeds. The adults are typical beetles with hard wing covers and usually a shiny back (Figure 4).2,3 They prefer fields with debris cover and are usually more common in reduced and no-till systems.4


Ground beetle larva.
Figure 3. Ground beetle larva. Picture courtesy of Joseph Berger, Bugwood.org.


Adult ground beetle.
Figure 4. Adult ground beetle. Picture courtesy of Ken Chamberlain, The Ohio State University, Bugwood.org.

Green Lacewing

Green lacewing larvae are important predators of aphids, mites, sap-feeding, and soft-bodied insects. The larvae are alligator-like and have large sickle shaped mouthparts (Figure 5). The larvae are predaceous and are sometimes called aphid lions as they have been reported to eat between 100 and 600 aphids each.5 Adults are not always predators and can commonly be found feeding on flower pollen and nectar (Figure 6). Individual eggs are laid on the end of a long thin stalk to prevent predation by other green lacewing larvae (Figure 7).6


Green lacewing larva.
Figure 5. Green lacewing larva. Picture courtesy of Whitney Cranshaw, Colorado State University, Bugwood.org.


Adult green lacewing.
Figure 6. Adult green lacewing. Picture courtesy of Frank Peairs, Colorado State University, Bugwood.org.


Green lacewing eggs on threadlike stalks.
Figure 7. Green lacewing eggs on threadlike stalks. Picture courtesy of Whitney Cranshaw, Colorado State University, Bugwood.org.

What is the effect of Bacillus thuringiensis (B.t.) traited corn on beneficial insects?7

There are three considerations to this question:

  • Insecticide (which may kill the pest and any beneficial insects present) use is potentially reduced when corn products with a B.t. trait(s) are planted because B.t. traits are specific to certain insects. If insecticides are not applied, beneficial insects are allowed to survive and help protect plants from other insects.
  • Because target pests could be exterminated from the crop by the B.t. toxin, natural enemies relying on the pest for food are negatively affected. While possible, the crop protection benefits of removing pests likely outweigh pest reduction provided by feeding from natural enemies. Also, biological control often results from complex actions of natural enemy species and overall natural enemy benefit may not be greatly affected.
  • Finally, natural enemies feeding on pests after ingesting the B.t. toxin may be negatively affected by the toxin. This interaction has been demonstrated; however, the negative effects on natural enemies are thought to be relatively minor.

Mike Binsfeld
Channel Agronomist


Sources

1Walgenbach, J. and Schoof, S. 2015. Lady beetles. NC State Extension. North Carolina State University. https://content.ces.ncsu.edu/lady-beetles
2Raupp, M., Traunfeld, J., and Sargent, C. 2023. Predatory beetles. University of Maryland Extension. https://extension.umd.edu/resource/predatory-beetles/
3Hahn, J. and Kells, S. 2024. Ground beetles. University of Minnesota Extension. https://extension.umn.edu/nuisance-insects/ground-beetles
4Carvalho, C., Gareau, T.P., and Barbercheck, M. 2025. Ground and tiger beetles (Coleoptera: Caravidae). PennState Extension. College of Agricultural Sciences. The Pennsylvania State University. https://extension.psu.edu/ground-and-tiger-beetles-coleoptera-carabidae
5Komondy, L. 2022. Common green lacewing. Cornell Integrated Pest Management. Cornell College of Agriculture and Life Sciences. https://cals.cornell.edu/integrated-pest-management/outreach-education/fact-sheets/common-green-lacewing-biocontrol-agent-factsheet
6Varenhorst, A., Rozeboom, P., and Wagner, P. 2023. Green lacewings: Beneficial predators for both small and large-scale landscapes. South Dakota State University Extension. https://extension.sdstate.edu/green-lacewings-beneficial-predators-both-small-and-large-scale-landscapes
7Peairs, F.B. 2013. Bt corn: Health and the environment. Fact Sheet No. 0.707. Crop Series Production. Colorado State University Extension. https://agsci.colostate.edu/wp-content/uploads/sites/127/2022/03/BT-Corn-Health-and-the-Environment.pdf
Websites verified 10/29/25. 1110_708600