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.
1 It can cost $200-$500 for a solid wood door, and $500-$1,000 or more for a more decorative interior door in high-end wood like walnut or mahogany. 2  For example, Lowe's store brand ReliaBilt 30. 3  Wide 6-Panel Hollow Composite Door Slab costs about $33.
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.