Firefly Larva

Description:

These beetle larvae look like prehistoric armored insects. They have flattened dorsal segments that extend to the back and sides, like overlapping plates. Their pink and white ventral surface is more fleshy and contains a glow organ with photocytes (light cells) at the end of their abdomens, which create bioluminescent light. So, how does a beetle larva's bum become a light beacon? Here's how - the light cells need several ingredients in order to make light. They need luciferin, ATP, and luciferase. Luciferase is an enzyme that causes the luciferin to produce light, and ATP provides the energy to drive the chemical reaction. Interestingly, these ingredients are always present in the glow organ, but it doesn't always glow because oxygen is required for the chemical reaction to occur. No oxygen = no reaction. No reaction = no light. The firefly larvae control the oxygen supply, so when they need to glow again, they simply feed oxygen to their glow organ, and voilá—it creates light.

Habitat:

There were three larvae under a rotting log in a deciduous forest.

Notes:

Firefly larvae produce light as a warning signal to predators, since firefly larvae contain defensive steroids that are distasteful or toxic. In adults, however, light production relates to mate selection.