Springtails are wingless and do not fly but they can jump. Unlike grasshoppers, crickets, and other insects that use large back legs for jumping, a springtail uses a forked appendage called a furcula (located underneath the abdomen) to propel itself. When not in use, a furcula is tucked up under the body, set like a mouse trap. When it is released, it extends down rapidly sending the springtail forward. A springtail can jump many times its body length.
Despite their small size, springtails can occur in tremendously large numbers and are one of the most abundant insects. One source estimates you would find millions of springtails in one hectare (about 2.5 acres) of land. They are associated with damp conditions and are found in soil, leaf litter, lichen, under bark, decaying plant matter, and other areas of high moisture. They feed on fungi, pollen, algae, or decaying organic matter.
They are occur indoors for several reasons. They can be found in the soil of overwatered houseplants and sometimes adjacent areas. They also occur in damp areas with high moisture, e.g. around plumbing leaks and damp basements. They can also move in large numbers indoors from the outside when moist conditions exit around the home. Springtails can vary in abundance indoors from just a handful to very large numbers. Fortunately, however many you find, they are harmless to people and property and are just nuisances.
If springtails are migrating in from the outside, check around the house for moisture problems. This could include rainspouts that do not carry the water far enough away from the foundation, landscapes that slope towards buildings, or excessive irrigation. It could even be a moisture problem with the roof. Correcting existing moisture conditions will help decrease springtails. As we receive less rainfall, the number of springtails will also naturally lessen.
Although it may be tempting to spray a springtail problem with an insecticide, the products available are not very effective against them. Moisture control is the most effective strategy.