The twinkling fireflies of a summer night bring a little magic. If we think beyond the twinkling, we probably realize it is courtship in progress: the signals of males and females.
There are a couple dozen firefly species in New England, each with a unique series of flashes, from males in flight to females perched below. Beyond the magic, very few people have knowledge of the medical benefits as well: the use of a firefly's light-producing chemicals in bioluminescent imaging.
In decades past, millions of fireflies were collected by young and old—paid a penny apiece—and the two chemicals key to the firefly flash were extracted for use in the new and ever-growing field of medical imaging.
Firefly light is a chemical reaction that produces a uniquely efficient "cold light" that generates almost no heat. Because they produce little heat, the chemicals can be injected in living cells. Then specialized cameras track responses to the introduced chemicals.
Cancerous cells emit a light weaker than normal; heart disease is detected by a light stronger than normal. Other medical applications include tracking progressive diseases like multiple sclerosis. Bioluminescent imaging also detects the presence of E. coli both in water quality monitoring and the testing of food products.
Fortunately for fireflies, cold light and the chemical reaction involved can now be synthesized in the lab. Even so, firefly collecting for a few biomedical companies continues, but on a scale well below the days of old. Along with the magic of fireflies twinkling in the night, we can add appreciation for all of the medical advances made thanks to plant and animal species—fireflies included.