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Agronomic Crops Network

Ohio State University Extension


Time to Scout for Black Cutworm in Corn

black cutworm feeding above ground

We have started to see cutworm damage in Ohio corn.  Black cutworm (BCW) is the prime offender, though other species exist.  Adult BCW (moths) are migrants from the south that start moving into Ohio in April, and lay eggs that hatch into the cutworm caterpillars.  Although there are some hotspots for egg laying, these predictions are far from exact.  Moths tend to seek out fields with a lot of weeds, especially winter annuals such as chickweed, to lay their eggs. The eggs are laid in the weeds and the tiny larvae feed on the weeds until the weeds are killed by herbicide or tillage at which time the larvae will move onto the corn planted in the fields.  An additional concern related to corn is that most of the crop is being planted relatively late this spring. Corn will be rather small when larvae of these pests begin their heavier feeding. Thus, the potential for plant injury and subsequent economic losses will be much higher than normal because of the size of the corn.  Black cutworms go through seven instars, with only the last four producing the greatest amount of injury.

Insecticidal seed treatments do not offer much protection.  Some Bt corn train packages provide BCW protection and some do not (  Early detection of cutworm infestations and timely application of rescue treatments are the keys to black cutworm larvaachieving effective stand protection.  Start scouting for BCW as soon as the corn begins emerge.  Rescue treatments can then be applied if necessary.  If cutting is above ground, cut plants will likely recover if a timely rescue treatment is applied.  In contrast, below ground feeding is generally characterized by by wilting plants that have been cut below the growing point, or plants cut off before emergence, and is harder to recover from.  Soil moisture conditions can sometimes dictate where you might expect to find cutting with above ground cutting occurring under moist soil conditions and below ground cutting occurring under dry soil conditions.  Treatment is warranted when visible cutworm injury is observed on 3% to 5% or more of a stand.   If a significant cutworm infestation is detected too late, cutting has occurred below ground and below the growing point, then a rescue treatment may achieve only marginal results.

More information about cutworm biology, scouting, and management can be found at

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.