Greatest loss with old plants and young larvae. Older plants have increased risk of damage at or below the growing point which would lead to serious stand and yield loss.
Young larvae have a longer feeding life remaining and can therefore do greater economic damage.
Excessive rainfall in the springtime often restricts planting at a critical time. However, this spring maximum provides a useful recharge of the soil's water holding capacity. Fall precipitation may delay harvest. Mid-season clear skies may result in drought stress during pollination but they also contribute the abundant, uninterrupted solar radiation necessary to produce the high corn yields typical of the U.S. Midwest. Low temperatures early and late may restrict season length and therefore yield potential.