(The word of the day is a random word on a random page of the Torre-Bueno Glossary of Entomology)

Multisetiferous, bearing many setae

Setae are sclerotized hairlike projections of the cuticle. People often use the words “setae” and “hairs” interchangeably. Caterpillars have two types of setae: primary and secondary. The primary setae are mostly homologous (shared) across lepidopteran families. Each setae is named with a letter and number related to its position on the body. For example D1 is dorsal setae #1. Any differences in the number or arrangement of primary setae can be useful in diagnosing the family, genus, or species of a caterpillar. Secondary setae are only present in a few groups, the ones which tend to be exceptionally hairy. Thus, a wooly bear would be deemed multisetiferous.

Some of my Acronicta species are multisetiferous, like this fuzzy Acronicta americana. Just look at those tufts!