Awoman has a large garden and decides this year she will not let the pests get beyond control. at the earliest sign of insect pests, she applies an organic insecticide and continues to apply it every month throughout the growing season. the next year the woman decides not to use any insecticides, thinking that she must have eliminated the pests with the prior year's treatments. unfortunately, the pests reappear in numbers greater than she has ever seen before, and her crops are destroyed. investigating this phenomenon, she learns that she has just experienced a phenomenon known as: