Bagworms are becoming active, particularly on junipers and arborvitae The young are hatching from their mother’s bag, release a silk thread that lowers them to another part of the same plant or, if the wind is right, carries them off to one nearby.
Watch for defoliated areas where the young are feeding. Clip off small infested branches and drop into soapy water.
Garden centers have a number of insecticides, organic and not-so, available. Later, as the bags get larger and more visible, handpicking can be fun and effective.
El Viejo
I watched a bluejay enjoying the delectable (at least to him) worms just the other day. He spent some time picking something from several remaining bags on our sourwood tree. We have been known to use fire to eliminate the bags as well.
Bagworms are easy to kill. Make a spray solution of water and liquid dish soap. (Or use Safersoap Bug spray.) You don't even have to clip the branches. Just saturate the bags. Check the next day to make sure you got them all.