Scale insects are a large and diverse group of small insects that belong to the order Hemiptera, suborder Sternorrhyncha. They have a waxy covering that protects them from predators and insecticides, and they feed on plant sap by piercing plant tissues with their mouthparts. Some scale insects produce honeydew, a sugary substance that attracts ants and can cause sooty mold to grow on plants. Scale insects can damage or kill plants by reducing their vigor, causing leaf drop, or transmitting diseases. There are many types of scale insects, such as soft scales, armored scales, and mealybugs, each with different host plants and life cycles.