The bagworms belong to the superfamily Tineoidea, which is a basal lineage of the Ditrysia (as is Gelechioidea, which includes case-bearers).

However, a few species can become more serious pests, and have caused significant damage e.g. to wattle (Acacia mearnsii) in South Africa and orange (Citrus × sinensis) in Florida.

If detected early, picking the cases from the trees while in their pupa stage is an effective way to check an infestation; otherwise, insecticides are used.

One bagworm species, the fangalabola (Deborrea malgassa) of Madagascar, is in some places encouraged to breed on wattle trees, because its pupae are collected as a protein-rich food.

More specialized species exhibit a greater variety of case size, shape, and composition, usually narrowing on both ends.

The attachment substance used to affix the bag to host plant, or structure, can be very strong, sometimes requiring a great deal of force to remove.

The adult males of most species are strong fliers with well-developed wings and feathery antennae but survive only long enough to reproduce due to underdeveloped mouthparts that prevent them from feeding.

[citation needed] One bagworm species was found to eat an orb-web of Plebs sachalinensis (Araneae, Araneidae) entirely.

Since the eggs are very hard-shelled, they can pass through the bird's digestive system unharmed, promoting the spread of the species over wide areas.