Fire Flies vary in size according to their type, from the size of ladybirds to that of small scarab beetles, and have evolved a unique defence to spiders and other predators-they spit fire from small holes in their sides. They are a deep violet in colour, and glow at night with a soft purple light as they feed on nectar from certain flowers. Should they get caught in a web, or jumped on by a praying mantis or some other predator, they send out a two second burst of flame that is caused when chemicals in their blood react with oxygen in the air, which they can repeat up to five times in twenty-four hours.
This short burst is hot enough to burn through any spider web and injure or kill any nearby insect, and is enough to hurt even a bird or a human. Whilst one of these insects cannot case much harm, they tend to fly in groups, and if one is killed or swatted at, the others will attack. If their nests are damaged, then, much like Crystal Hornets the whole hive, thousands strong, will swarm out and try and kill whoever did it, and in those numbers they can, acting together, even burn a human to death with mutiple bursts of hot flame, hot enough to ignite linen and sear flesh.
If twenty or more can be caught and crushed, and then are prepared by a skilled wizard before they decompose, they can be used in a short term potion that can be used to change someone's voice, that is useful for disguising oneself or impersonating another person.