This is a mystery solved for me. For ages I have wondered what creature hides within this clump of twigs, being the morally inclined naturalist, i was reluctant to pry the home open to appease my curiosity. But now I know!
here's a passage from the excellent writeup
"Bagworms are a group of highly specialized lepidopterans belonging to the family Psychidae and exhibit extreme development of sexual dimorphism. Males are winged whereas females lack functional appendages. Larvae of both males and females, soon after hatching from the eggs climb up to the top of their host plants in order to have an access to the soft and palatable tips of the growing shoots. They construct a small but tough bag of silk of either cylindrical or conical shape and glue small fragments of plant tissues around their cases. Larvae always keep their body inside the cases. While moving about, their head and thorax are protruded out so that they move forward on their thoracic legs dragging the case behind them, which is gripped by hooks on the abdominal prolegs. When taking rest, the rims of the cases remain attached to a twig by means of silken thread so that the cases hang vertically with both their openings remaining closed."