Sealing a house against insects involves conducting a comprehensive inspection of the entire structure to identify potential entry points. Use appropriate materials to seal cracks, gaps, and holes in walls, foundations, and around windows and doors. Ensure that screens, door sweeps, and weatherstripping are in good condition and replace them as needed. Manage moisture levels, eliminate standing water, and keep the area around the house free from debris and overgrown vegetation to deter insects. Implementing these measures significantly reduces the likelihood of pests entering your home.