Plectrocnemia caddis larvae have no mobile case, no chelae (pincers) and they have a speckled head pattern. There is a curved line of small dark spots running across the middle of the head.
Plectrocnemia larvae are occasionally found in gravelly streams with slow to moderate current speeds throughout New Zealand.
They construct delicate filter-feeding nets to trap drifting particulate food items, possibly including other invertebrates and plant fragments.
Plectrocnemia larvae can be an indication of good water quality, particularly if they are found along with a range of mayfly and stonefly taxa. They have tolerance values of 8 (hard bottom sites) and 6.6 (soft bottom sites).