This looks like springtails. They feed primarily on algae, fungi, pollen and decaying organic matter. They are associated with dampness, organic matter, and mold. They have a forked appendage in the rear that enables them to jump. Springtails usually occur in the soil, but may also be found under potted plants, and decaying vegetable matter. They are harmless. They probably hatched on a warm day and outdoors they can be everywhere. Here is more information https://extension.umd.edu/hgic/topics/springtails
 
Marian