Already have Bifen (from you) when I had bag worms. What amount of Bifen mix is appropriate with 3 gallons of water/spray?
Go with 1 oz per gallon of water. And definitely add some SPREADER STICKER to insure good coverage of the spray.
Spreader Sticker: https://www.bugspraycart.com/insecticide/additive/spreader-sticker