The famous tent caterpillars are small Lappets belonging to the Malacosoma genus. The LepIndex references 25 species, all occurring in the Northern Hemisphere, both in North America as in Eurasia.
The caterpillars are usually colorful and group together in a silk nest. Some species can be locally abundant and even become a serious pest. The rearing is easy. Eggs overwinter in the fridge. Moths appear late spring, early summer.