In the early 1990s, average annual precipitation suddenly increased about 20 percent across the eastern Dakotas and western Minnesota. Rain and snow do not fall every day, so this increase in annual moisture has come in spurts. Essentially, our wet periods have been getting wetter and our rainy summers have been getting rainier, leading to persistent, large puddles of rain water and, at times, an intolerable mosquito population. Notably, in the early 1990s, there was no organized mosquito spraying program.
I was reminded of all of this last week when a night of mosquito spraying led to a noticeable kill of Monarch butterflies and a public outcry. Because of the concern over the Monarch's shrinking population, this loss was unfortunate; perhaps even tragic. Perhaps the way we spray for mosquitoes should be rethought. However, this should be weighed against the fact that mosquito counts last week were the highest in five years and some parts of the region have evidence of mosquitoes carrying the West Nile virus.
