Back to top

Section 26.6.1: Corn Flea Beetle

Corn flea beetle, Chaetocnema pulicaria, vectors the bacterium, Erwinia stewartii, which is the pathogen that causes Stewart’s wilt.

Time of concern: Seedling through mid-whorl
Key characteristics: Black or brassy in color, the corn flea beetle is about 1/16 inch in length and often jumps when disturbed. Beetles chew narrow channels in corn leaves. For a description of Stewart’s wilt, see Section 26.5 Stewart's wilt.

Management Option Guideline

Sampling for flea beetles should take place from plant emergence through mid-whorl. Count the number of beetles on ten plants at ten sites. Based on research in New Jersey, insecticide sprays to susceptible varieties not planted with treated seed are recommended for susceptible varieties when populations exceed six beetles per 100 plants until the mid-whorl (knee high) stage. 

Natural enemies

Little is known about the impact of natural enemies on corn flea beetles. Use Natural Enemies of Vegetable Insect Pests for identification of natural enemies.

  • Collops vittatus
  • Microtonus vittatae
Forecasting If the disease and corn flea beetles were prevalent the previous season and the winter was mild, seed treatment or in-furrow insecticides should be considered if the variety is susceptible to Stewart's wilt. Foliar applications should be considered in susceptible varieties without in-furrow or seed treatment if populations exceed the threshold. Forecast of infestation: the Iowa State University Model predicts the prevalence of Stewart's Wilt Disease based on average temperatures for the months of December, January and February. Warm winter temperatures suggest that survival of large corn flea beetle populations is likely. Therefore, a high prevalence of Stewart's Disease is predicted, if the mean monthly temperatures for December, January and February are each above 24° F. If two of the three months average above 24° F, the risk is moderate to high (yellow dots on map). If one of the three months averages above 24° F, the risk is low to moderate (green dots on map). If all three months average below 24° F, survival of the beetle is unlikely and the risk of Stewart's Disease is negligible. 
Resistant varieties Plant varieties resistant or tolerant to Stewart's wilt whenever possible. Although they may not eliminate infection, they are the best means of disease control. See Section 26.1 Recommended Varieties.
Planting date Fields planted midseason generally have lower beetle infestations than early or late planted fields.
Seed selection/treatment For susceptible and moderately resistant varieties of sweet corn, especially any early-planted varieties, it is recommended to purchase seed already treated with an effective systemic insecticide. Stewart's wilt can be transmitted by seed, but this occurrence is rare. 
Postharvest Fall plowing may reduce overwintering populations.
Insecticide Resistance Management

The Insecticide Resistance Action Committee (IRAC) has classified insecticides into resistance management groups. Most insecticides include an IRAC group number on the front page of the label. Alternating between insecticides with different group numbers will help avoid the development of resistant insect populations.

Crop rotation,
Site selection, and
These are not currently viable management options.
Pesticides Cornell Integrated Crop and Pest Management Guidelines for Commercial Vegetable Production