Often the adult insect will show little resemblance to the early instars.
I've only been lucky enough to see this first hand once thus far but it's a fascinating process to watch.
The little bug I found today whilst walking around woodland in my home town of Cranbrook is a Forest Bug (Pentatoma rufipes) and is possibly a third instar. I often see these towards the later stages of winter with the adults appearing around June-November.
The adults feed on fruits and also caterpillars plus other insects.
3rd instar of the Forest Bug
Final instar of the Forest Bug
The emergence (note the pale colour at this stage)
The adult Forest Bug