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Mild winter temperatures during the months of December, January and February increase the potential for high populations of flea beetle. The flea beetle model for Missouri is calculated by adding together the average monthly winter temperatures for the months of December, January and February. If the average monthly temperatures for these months add to less than 90 degrees, then the risk of economic flea beetle infestations is low. If the total is between 90 degrees and 100 degrees, then moderate flea beetle damage can be expected. Heavy damage is possible if the three monthly averages total 100 degrees or more. Data from Commercial Ag Weather Stations located around the state are summarized by region and specific counties in the following table. Corn most at risk are those fields located in areas where the cumulative average monthly temperatures for the months of December through February are in excess of 90 degrees and seed treatments were not used. Rescue treatments are also effective in managing this pest and are discussed in detail in the following table. My thanks to Jim Jarman (regional agronomy specialist) for providing the following table.

Table 1: 2007 Corn Flea Beetle Predictions for Missouri

Biology/ Damage
Flea beetles are small, dark, jumping beetles that overwinter as adults. In early spring they move to seedling corn and feed on plant foliage from the time of plant emergence through about the fourth-leaf stage of growth. Adult beetles strip the chlorophyll layer (green tissue) from the surface of seedling corn leaves resulting in the formation of "window panes" or translucent areas in leaf surfaces. Damage is often seen as translucent tracks or lines which run parallel to the veins of the corn leaf. Heavy flea beetle infestations cause plants to look "tattered" and wilted, similar to the type of injury caused to seedling corn when blasted by blowing sand. The most injurious flea beetle attacking corn is the corn or maize flea beetle. Typically, infestations are most severe in years where mild winters allow for increased survival of adults and cool temperatures and drought conditions during spring result in slowed growth of corn plants. Flea beetles may transmit Stewart's wilt (a bacterial wilt) to corn, although most field corn has resistance to this plant pathogen. The economic threshold for implementation of control methods for flea beetles in field corn is an average of five or more beetles per corn seedling up through the four-leaf stage of development. To scout for flea beetles, examine corn plants for feeding damage and determine the average number of flea beetles present per corn plant. This is most readily accomplished in the early morning or late afternoon by walking slowly through the field and counting beetles as they feed on leaf surfaces. Remember, flea beetles are easily recognized by their jumping ability similar to grasshoppers. Although several species of flea beetles can be found in field corn, the maize or corn flea beetle typically causes problems in this crop.

Management Options
Corn most at risk from flea beetle damage are fields located in areas where winter temperatures are elevated (see table) and corn plants are not protected with a commercially applied seed treatment. Many seed treatment trials have shown quick suppression of flea beetle numbers during early-season feeding by this pest. In addition, the widespread use of seed treatments for corn during the past few years may be suppressing flea beetle problems statewide, similar to what Bt corn has done to the European corn borer populations throughout the Midwest. Rescue insecticide applications are also effective management options for flea beetles. Producers should scout seedling corn for the presence of flea beetles and apply a rescue insecticide treatment when the flea beetle population reaches or exceeds the economic threshold of an average of five or more flea beetles per corn seedling up to the four-leaf stage of plant development

Insecticides and rates labeled for flea beetle management used as rescue treatment on field corn include the following: