It is found in abundance throughout North America and Europe, and likely has a cosmopolitan distribution.

Willowsia buski is a medium-sized springtail, averaging 1-2mm in length.

It has a smooth, dark-purple to black appearance, with fine setae present over the body's surface.

The head is generally a lighter color, allowing for easy distinction from similar species.

Like all members of Entomobryidae, it has four, roughly equal antennal segments.