This document provides an overview of entomology and common insects. It begins with definitions of what constitutes an insect, describing their main body parts and types of mouths, legs, wings, and life cycles. It then lists and describes the top 20 most common insects that concern the public, including aphids, spider mites, lace bugs, scales, whiteflies, borers, grubs, tent caterpillars, and others. The document also covers some common household or structure-invading insects like beetles, termites, ants, carpenter ants, bees, wasps, and spiders. It concludes by acknowledging the photo sources.