Springtails (Order Collembola).
Springtails are minute, primitive insects that can occur in enormous numbers (50,000 per cubic foot) in forest litter and organic soils. Springtails can be found outdoors in any moist situation, usually feeding on algae, fungi and decaying vegetation. Springtails are extremely sensitive to moisture, if their normal environment becomes dry, they will actively seek moisture, sometimes invading homes and similar structures where they are most commonly found near sources of moisture such as kitchens and bathrooms. These insects are not known to bite or cause damage to stored food, wood or fabrics. Springtails can persist indoors if adequate moisture is found and if fungi, mildew or decaying vegetable matter exist in sufficient quantities, but in general, they are only occasional or incidental visitors in structures. If springtails persist indoors, the best control is to decrease the humidity and remove anything found to be moldy or in a state of decay. Household aerosols (like Raid) or persistent products like cyfluthrin (sold as Bayer Advanced Home Insect Control can be used indoors to control them. Treating the exterior walls and foundations with cyfluthrin or persistent products registered for this use may aid in preventing their entry during warmer months of the year.
Be sure to read and follow all instructions on the label before using any pesticide.