Springtails
Springtails are frequently found in new homes feeding on surface mold growing on structural wood that became wet during construction. They are approximately 1/16 inch long, and quickly use a forked appendage under their body to spring. Springtails are harmless, but can become a major nuisance when they begin multiplying.
These insect reproduce quickly, and can be found in drains, sinks, tubs, and potted plants. They feed on mold, fungus, and decaying matter, and prefer to live in damp environments. If you see them around your drains, you can begin treating the problem by making sure your drains are clean. Setting up a dehumidifier will significantly reduce moisture in a space, and may also deter Springtails.
If the nest is too large, treatment is recommended.