The first photo (image file name 6102) does show a bagworm bag/cocoon, but it is old and already empty as we can see the pupal skin pushed out of the bottom of the bag. (This is what will happen when the adult male moth has emerged, and that took place sometime last year.) The simplest intervention is to hand remove any bags you can find, since female moths never leave their bag and use the bag as a sheltered spot to lay eggs for the next generation. If you needed to treat a plant, the linked page provides more information about the insect's life cycle and what lower-toxicity insecticides to try. Still, on deciduous plants like Japanese maple, their feeding damage is usually inconsequential and doesn't require intervention since the plant is not seriously damaged unless populations become very large. (The potential for long-term damage to foliage is greater on needled evergreens like juniper and arborvitae.)

The object in the second photo is not a bagworm and looks like the cocoon of a moth in the family Saturniidae, sometimes referred to as wild silk moths (even though they are not related to true silk moths; these are native). Based on its size and shape, we'd guess that this particular cocoon belongs to a Polyphemus moth, and thus would emerge around late April or early May depending on temperature trends. (If the cocoon has a large hole in one end, it's old and empty, with the moth having already emerged sometime last year.)

Miri