Oecetis caddis larvae construct delicate mobile cases made of sand grains. They have a pale head with dark speckles, and their hind legs have long, curved claws. Like other leptocerids their hind legs are much longer than their fore legs.
Oecetis larvae are common in many slow-flowing streams and rivers with sandy beds.
They are predators, preying on other small stream invertebrates.
Oecetis larvae are found in streams of moderate to good water quality so they are not necessarily an indicator of pristine conditions. They have tolerance values of 6 (hard bottom sites) and 6.8 (soft bottom sites).