A female monarch lays its eggs (1) on a sprouted milkweed plant. The eggs hatch in four to five days producing tiny yellow, black and white banded larvae (caterpillars). These caterpillars (2) will feed solely on milkweed and eat enormous quantities because they are growing fast.
Roll-up door spring repair or replacement is usually around $200 - $250 for a 2 car door. If the brackets need to be disassembled to remove the springs due to the shaft not sliding sideways enough it will cost you an additional $50 - $100.
Door repair/replacement - depends on the damage done. Likely repair cost if fairly minor damage that can be patched and repainted minimum probably $150-200 by a Handyman, more likely about $200-300 including repainting so it all matches or putting solid brass finish plate ovear damaged area to hide it.