Caddisfly nymph (Genus Pycnocentrodes) Stony cased caddisfly

Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Hexapoda
Class: Insecta
Subclass: Pterygota (caddisflies)
Order: Trichoptera
Suborder: Brevitentoria
Family: Conoesucidae
Genus Pycnocentrodes
Common name: Stony cased caddis

Pycnocentrodes caddis larvae construct mobile cases by binding together sand particles with silk covered in sand grains and small stones. Pycnocentrodes larvae often attach larger stones or snails to the sides of their case. They hide in this case from predators.
The top of their head is much flatter than other sandy/stony cased genera like Pycnocentria or Pycnocentrella.
They are common inhabitants in cool, clear water streams with stony or gravely beds, both in bush and farmland areas.
They are collector-gatherers feeding on fine organic matter and grazing on streambed algae.
They pupate by closing the end of the case. After hatching the exit the case, surface and fly away as an adult caddisfly.

1-pycnocentrodes huia rubymontage b 650.jpg

Stony cased caddis most likely Pycnocentria.-001.jpg 

Thanks to Wikipedia for text and information: