What are the differences between spiders and insects? Spiders have two main body parts, eight walking legs, simple eyes and piercing jaws (fangs), abdominal silk spinning organs, anterior abdominal genital opening and can't fly. Insects have three main body parts, six walking legs, compound eyes, antennae, chewing jaws (mandibles - often secondarily modified), posterior abdominal genital opening and can fly.
All spiders produce silk, a thin, strong protein strand extruded by the spider from spinnerets most commonly found on the end of the abdomen. Many species use it to trap insects in webs, although there are also many species that hunt freely. Silk can be used to aid in climbing, form smooth walls for burrows, build egg sacs, wrap prey, and temporarily hold sperm, among other applications.
All spiders except those in the families Uloboridae and Holarchaeidae, and in the suborder Mesothelae (together about 350 species) can inject venom to protect themselves or to kill and liquefy prey. Only about 200 species, however, have bites that can pose health problems to humans. Many larger species' bites may be quite painful, but will not produce lasting health concerns.
A couple of ideas to get rid of spiders before you have a problem
Change the exterior lighting on the building. Spiders are smart and know that other bugs are attracted to lights. They will hunt and build webs in these areas. Try to limit unnecessary exterior lighting to reduce the population so close to the home.
Tall grass right up against the house and overhanging trees will harbour insects and attract spiders. Keep your property maintained. Weeds should be kept mowed and garden beds should not be right up against the foundation.
Open water on the property provides a breeding source for many insects, including mosquitoes and midges, which in turn attracts spiders. Homes built right near a lake are prime candidates for spider infestations. Houses next to open fields are also common sites of spider infestations. In these areas winds carry spiderlings into the area, where they end up on the sides of the house. Once spiders build up outdoors on structures, they naturally filter indoors through cracks and crevices around windows, doors, attics, and crawls spaces.
Large gaps in siding, unsealed openings around pipe penetrations, unscreened vents and windows will allow spiders to enter the home. A tube of silicone will do wonders for pest prevention. If you can keep them out you don't need to use other methods.
Spiders are opportunists and are attracted to areas where food (insects) and moisture are abundant. Eliminate insect breeding areas, reduce moisture, repair leaking pipes, and free standing moisture on your property.