There are four main places where house sealing is commonly used in the home to close off entry points and keep pests out:

1. Cracks, Gaps, and Holes in the Foundation or Other Areas of the Home. These are the most common points of entry for pests to welcome themselves to your home. Usually, the cracks, gaps, and holes are tiny but still allow for pests like ants and small insects to enter. Pest control technicians can easily fill these areas with weatherproof silicone caulking. 
2. Vents and Window Screens. Flying and crawling insects love to use poorly screened areas to enter, such as non-screened air flow vents and window screens that are missing or in poor repair. This is a common finding in older homes and often will result in a bee or wasp infestation in the attic. Other times, cockroaches will crawl right in your window through a faulty screen.
3. Doors and Windows. Another very common point of entry is the gaps around doors and windows that allow for all kinds of pests to enter. These gaps could be caused by neglect on the homeowners’ part, such as when doors and windows are left open. They can also be caused by improperly sealed doors and windowpanes. Often, sliding glass doors are the likely offender because they are hard to seal completely. 
4. Property Walls. To prevent large pests such as snakes, coyotes, and raccoons from entering your property, a perimeter fence can act as a protective wall to keep pests out. It’s important to make sure that there are no gaps at the base of the fence, or something might squeeze through.