most destructive small creatures in the world

Though not destructive in the structural sense, Tsetse flies are estimated to be responsible for the endangerment of anywhere between 250,000 to 300,000 people annually. Tsetse flies are large biting flies that inhabit large regions of Africa between the Sahara and Kalahari Deserts. They live by feeding on the blood of vertebrate animals and are the primary African biological vectors of trypanosomes, which causes human sleeping sickness and animal trypanosomiasis, also known as nagana.