Rising temperatures, drought, pests and diseases are moving north into the U.S. heartland and are increasingly posing a threat to the wheat crop. An insect called the Hessian fly is reducing crop yields by 10% a year in the Midwest. Average temperatures in the Midwest have risen by 2 degrees since 2000, and periods of time between rainfalls is lengthening. Conditions in some areas of the Midwest are getting to be more like those in the Middle East.