An unwelcome buzz — wasps — this spring forced teachers to shutter classroom windows. Anecdotally, there seem to be more than usual hovering this spring, following a somewhat mild winter in Iowa, according to weather experts. Iowa State University professor of entomology Donald Lewis said he has heard from Iowans who have felt there were more of the insects than usual. He, too, suspects it was a “good winter” for the them. Gabrielle Smithman, a teacher at Merrill Middle School in Des Moines, experienced the effect of that good winter.