Search

Except for a few extremely cold days, Iowa has experienced a mild winter. In fact, February 2024 was the warmest February in Iowa’s weather history, and this winter is one of the warmest ever for the state. In addition to warmer temperatures, the total snowfall for our state has been low (Figure 1) and below average compared to a normal year (Figure 2). Much of the snowfall this winter was during a two-week period in January. As a result, many people are asking how a dry and mild winter might impact overwintering insects.

Bean leaf beetle adults (Photo 1) are susceptible to cold weather and most die when air temperatures fall below 14°F (-10°C). However, they have adapted to winter by protecting themselves under plant debris and loose soil. Each spring, adult beetles emerge from their overwintering habitat and migrate to available hosts, such as alfalfa, tick trefoil, and various clovers. As the season progresses, bean leaf beetles move to soybean and other hosts. While adult activity can begin before soybean emergence, peak abundance often coincides with early-vegetative soybean.