As Moritz Fischer explained, the rig for this bumblebee by Leonie Keist is quite simple. The exoskeleton limits movement, so the rig doesn't require many controls, with the standout feature being the wings.
In addition to the standard controls, an automatic flight animation can be activated. This utilizes expressions to control the wing base, making all rotation axes move simultaneously for a realistic flight motion. The speed and range of the wings are adjustable to suit your needs.
If you're interested in seeing more rigging showcases, we recommend checking out Moritz Fischer's LinkedIn page. He shared a whole series of similar videos featuring various creatures, along with insights into the production process, including a crab, a meerkat, and a muscle simulation for a biped character:
