I have used Bernat’s glow-in-the-dark yarn to make this, but that yarn is listed as optional in the pattern, as I understand it is not readily available anymore.

The pattern is based on Europe’s most common firefly, Lampyris noctiluca, which is also known as the common glowworm. It is the female that has the strongest glow, partially because she does not have wings. She sits high up on tall grasses and attract the much smaller (and winged) males. The fireflies are actually beetles, though their common names suggest otherwise.

Because of the difference between the sexes I have chosen to include “female” in the pattern name to avoid any confusion :)