"nhộng Tằm" worm cocoons - vietnam

If you know the genus of the insect larvae that makes those cocoons, please post a comment!

Nhộng Tằm worm cocoons (Vietnam)

Nhộng Tam worms are a delicacy in some parts of Vietnam, but I didn't get a change to try that for diner.­

Those are not Silkworms (Lepidoptera), but they produce a similar cocoon that is harvested by the tribe people in Northern Vietnam.­