Arctiinae

The Arctiinae (formerly called the Arctiidae) are a large and diverse subfamily of moths, with around 11,000 species found all over the world, including 6,000 neotropical species. This group includes the groups commonly known as tiger moths (or tigers), which usually have bright colours, footmen, which are usually much drabber, lichen moths, and wasp moths. Many species have "hairy" caterpillars that are popularly known as woolly bears or woolly worms. The scientific name refers to this (Gk. αρκτος = a bear). Caterpillars may also go by the name "tussock moths" (more usually this refers to the Lymantriidae, however).
The most distinctive feature of the subfamily is a tymbal organ on the metathorax. This organ has membranes which are vibrated to produce ultrasonic sounds. They also have thoracic tympanal organs for hearing, a trait which has a fairly broad distribution in the Lepidoptera, but the location and structure is distinctive to the subfamily. Other distinctive traits are particular setae ('hairs') on the larvae, wing venation, and a pair of glands near the ovipositor. The sounds are used in mating and for defense against predators.[6] Another good distinguishing character of the subfamily is presence of anal glands in females.