Favoritos de huwalu_ka_using

L2 Dytiscus sp. larva, caught in a bottle trap inspired by Inoda and Ladion's (2016) "New box trap for large predaceous diving beetles" baited with pig liver and placed in a clearing of sedges & Typha in a beaver pond.

All I can say is for certain is that they are not a D. hatchi larva. They do, however seem to be a caddisfly specialist such as D. harrisii based on morphological features such as a relatively small head and shorter mandibles as described by Leclair et al. (1986) in "Prey Choice in Larval Dytiscus harrisii Kirby and D. verticalis Say", and on account of behaviour and ability to predate caddisfly larvae as viewed in a captive setting.

Update: they have since ecdysed once and are now L3, pictures of caddisfly larvae hunting added.

Update: they have now pupated, length at the time of pupation was ~62mm, new pictures added. Pupation container 8 cm × 10 cm × 28 cm filled with 5 ½ cm of damp peat.

Update: they have reached adulthood, confirmed male D. harrisii—final adult length of ~39mm.

Saw a Dytiscus observation here from a long time ago that I saw the subapical fascia on the elytra and I wanted to confirm if it was actually Dytiscus harrisii or not, turns out it was!
Guessing that the ponds here have a population of them—it certainly would make sense considering the amount of caddisfly larvae I've seen around the plants in this pond.

Caught in a bottle trap baited with pig liver placed among some typha that was left out for 24 hours, ~39mm. Missing right mesothoracic tarsus, left maxillary palp, & has a small bite out of their left elytron.