Pycnocentrella caddis larvae construct mobile cases covered in sand grains. They look much like the more common Pycnocentria, but Pycnocentrella have a distinctive comb-like row of hairs on the front/side edge of the pronotum (first segment behind the head).
Pycnocentrella larvae are much less common than the similar-looking Pycnocentria, but they are most likely to be found in gravelly, bush covered streams.
They are collector-gatherers (feeding on fine particulate matter including algae) and shredders (feeding on leaf litter).
The presence of Pycnocentrella larvae indicates good habitat and water quality, particularly if a range of mayfly and stonefly nymphs are also present. They have a high tolerance value of 9 for hard bottom sites (there is no soft bottom value).