Spray affected plants with a ready-to-use systemic insecticide that contains acephate, imidacloprid or dinotefuran. Systemic formulas do not kill bagworms directly. The active ingredient is absorbed into plant leaves and needles, and then circulated throughout the plant. The insects die when they feed on plant parts and plant sap.
Depending on the size of your garage, insulating the walls with batts of R-13 will typically run you about $400, the ceiling $600, and the garage door will cost about $600 if you do it right (See image to the left). You can use the pink Styrofoam stuff from Home Depot, but that will only insulate your door to about R-6.
1 Building a garage typically costs about $35-$45 a square foot, or $8,400-$10,800 for a standard single-car garage and $13,300-$17,100 for a two-car garage.2  A custom outdoor greenhouse with a solid foundation, heating and electricity starts at $10,000-$20,000 for a small structure, but can cost $25,000-$50,000 or more. A bedroom addition consisting of 500 square feet of new floor space with two bedrooms and a bathroom can cost $50-$250 or more a square foot, or $25,000-$125,000.