Develop a list of key pests as an initial step in IPM planning for vegetable insects

Identify the pests your vegetable crop is at risk for as an initial step in pre-season IPM planning.

Proactive insect management requires anticipating pests that pose a major risk to your crop. This can be a challenge, given the myriad of insects that damage vegetables. Pest managers can take a cue from risk assessment, which aims to anticipate and prioritize threats. In risk assessment, risk is the product of two things, the chance an event occurs, and the severity of the consequences if it occurs:

Risk = likelihood an event occurs X severity of its consequences

Risk increases for events that are highly probable or have major negative effects on human goals.

In a pest management context, pests that are consistently present and cause economic damage pose a major risk and should take top priority. For example, sweet corn insect pests include over 10 insect species. However, of these, corn earworm, western bean cutworm and European corn borer are most consistently present and cause direct damage to corn ears that reduces marketable yield. In other words, there is a relatively high likelihood they will cause problems and the consequences will be severe if problems are not detected and managed. These pests pose a major risk and should be a focus of monitoring and control efforts.

Other pests may only be sporadically present, but cause severe damage when they do occur. Prior to the growing season, make sure to understand the conditions that favor these pests so you can take preventive measures in the event these conditions occur. According to Michigan State University Extension, a good example of such a pest is corn flea beetle, the vector of Stewart’s wilt, a disease of sweet corn. This pest may not be a problem in cool winters that limit overwintering survival of beetles. However, when average temperatures between January and December are over 30 degrees Fahrenheit, a higher percentage of beetles will survive, increasing the risk of Stewart’s wilt in seedling sweet corn. The consequences are potentially severe, as Stewart’s wilt can cause significant yield loss. When these conditions occur (weather data for locations near you are available at Enviro-weather), a wilt-resistant variety can be planted to limit this problem.

For pests that are consistently damaging or cause occasional but severe damage, being proactive is essential. In contrast, other pests may be extremely rare or may be present but cause little economic damage. For these pests, reactive management is less risky.

When developing your plans for insect monitoring and control, focus on key pests that pose the highest risk of damaging your crop


Severity of damage

Likelihood of damage


Major economic damage

Moderate economic damage

Negligible damage

Near certainty

Key pest

Key pest

Not key pest

Possible, not certain

Key pest

Not key pest

Not key pest


Not key pest

Not key pest

Not key pest

Example of a list of key insect pests of sweet corn, including conditions that favor sporadically important but damaging pests

Consistently present and damaging pest

  • Corn earworm
  • Western bean cutworm
  • European corn borer

Sporadically present but damaging pests

  • Wireworm: Sweet corn is planted after alfalfa, former sod or fallow
  • Corn flea beetle: Winter temperatures averaging more than 30 F during December and January
  • Seen corn maggot: Early planting in cool soils or planting in soils with high organic matter
  • Corn leaf aphid: Problem in corn planted after mid-June and when winters are followed by dry conditions during the pre-tassel/silking stage

Related MSU Extension article

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