Answer: Without seeing them, I'm just venturing an educated guess, based upon your gardening region and the time of year. They may very well be bagworms. These little guys spend their time in a small cocoon with only their heads sticking out. Usually they cluster in conifers, but sometimes they appear on the sides of houses. They're not doing any damage to your garage door, and hosing them off is an easy way to get rid of them. They'll stop appearing as soon as the weather gets really cold. Next year, if there's a large enough population, natural predators will show up and feed on them.
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