Why are there cocoons on my yew shrubs?

i have six yew shrubs, two of which are not doing so well. there are cocoon-like things hanging down from the plant. the cocoon seems to be made out of the dead yew leaves. we've also found these hanging from our brick wall on our house. they're connected to the brick by some tough thread-like tissue. there are little larvae inside the cocoons. what is this, and what can i do to get rid of them?

Why are there cocoons on my yew shrubs?
They're called Bagworm Moths. They make their coccoons out of dead leaves of whatever plant they're on or near. If there's not alot of them, then they'll do very little harm, but if they overpopulate, you might want to spray a dilute solution of Malathion spray on them to kill them off.
Reply:you are getting what is called bagworrms spray them with an isecticide that is recommended for bagworms and alwaays follow the directions on the insecticide
Reply:They are bag worms and can be devistating to plants. The old fashion way to get rid of them is to pull them off and put them in a bucket of water or kerosene. The new way is to spray them with a pesticide. either way if you say they are on wall then i would say you have a problem.