Throughout history, pests have wreaked havoc on crops. One of the most notorious examples occurred in the mid-1800s during the Irish potato famine. The Great Famine caused the death of almost two million people. Its cause was a mold, or blight, that caused the failure of potato crops - a staple in the Irish diet. The spread of the blight was additionally facilitated and exacerbated by insects. Even today, it is estimated that plant diseases cause an annual percentage of 11 to 16 percent reduction in the value of corn, wheat, rice and potato harvests. Much of the diseases' transfers can be blamed on insects.