the wiring to each fly was made with green solder through winding wire to blend in as "grass" and the bodies and legs of the flys were constructed from the LEDs themselves. with hand cut wings hot glued on.
The green LED fiies used PWM out on Arduino Unos or Adafruit pro trinkets .
On some of the collections of Fireflies they had 2 LEDs, a green and a red, the red was used to show anger / agitation and was tied to the green, for dimming. tapping the glass jar several times would "anger" the fireflies.
The jars were labeled as experiments with an accompanying prop log book detailing collection methods and observations of the collections over time. Each jar had a different "personality" ranging from docile to aggressive, as reflected in the rate of lighting, and reaction to shadows and tapping.