Basements are cool, dark, often moist places that don't usually see a lot of human traffic. This makes them an excellent habitat for a wide range of insects, arthropods and other invertebrates. While these creatures can be unpleasant to encounter and are generally considered pests, most aren't dangerous or likely to infest the home. Being able to identify common basement bugs can help you decide which ones require control measures, and which ones can be safely left alone.
Crickets commonly invade homes, and a few species will even live and breed in basements. Shiny black field crickets often move in when night temperatures fall in the autumn. The brownish house cricket also migrate indoors during fall weather, but can live in the home all year. It may damage stored fabric, and prefers warm parts of the basement. Camel crickets, which are brownish humpbacked insects, prefer cool, damp locations and are a common basement dweller, but they rarely do any damage. The frightening-looking mole cricket also sometimes comes indoors when its underground tunnels become flooded, but usually does not stay.
These multi-segmented creatures come into the basement and first floor of a home via cracks in the walls and foundation. They usually live in the soil outside, and come in only if the basement is moist. Sowbugs are flatter and light gray, while pill bugs are dark gray to black, and capable of rolling into a tight ball. Neither type of invertebrate does damage to the basement or home.
These multi-segmented, many-legged creatures are usually brown or black with smooth, shiny bodies. In their natural outdoor environment, they prefer decaying leaf litter and other plant debris. Like sowbugs and pillbugs, millipedes need a moist environment. These creatures are vegetarians, and can live for several years. They are not poisonous and do not damage homes, but may be found around sumps or other areas where wet, organic matter could accumulate.
Often confused with millipedes, centipedes have fewer legs, long antenna, and are carnivorous. These creatures sport venomous fangs, and some species can cause a painful bite. However, they also keep populations of other pest bugs down. Remove centipedes if small children or pets frequent your basement. According to the University of Missouri, the common house centipede, a light gray creature with many long, feathery legs, cannot bite humans and consumes many household pests. It should be left alone unless the population presents a nuisance.
Basements provide a habitat for many different types of spiders. Some are harmless, some beneficial and some are poisonous to humans. Common house spiders and cellar spiders are harmless basement dwellers that prefer damp, warm conditions. Wolf spiders may live in basements with large numbers of crickets and other prey. These spiders are large and alarming-looking, but non-aggressive unless handled. Other species, including the black widow, brown recluse and hobo spider, may infest rarely disturbed parts of the basement. If these creatures live in your area, rotate your storage regularly, and keep clothing and toys in sealed bags or boxes.