Best Ever Q&A Space Our World Nature Evolution Prehistoric Life Dinosaurs Simple Creatures Insects & Spiders Fish Amphibians & Reptiles Birds Sea Mammals Land Mammals Ecology Animal Behavior Pets Farm Animals Plant Kingdom Plant Life History Science & Technology	Ecology Why are some insects called pests? What is acid rain? What is the greenhouse effect? Why are some animals endangered? What is ecology?   Previous: Back to Ecology Book: Best Ever Q&A Section: Nature Chapter: Ecology