Fireworm (Species)

"Their skin burns hotter than the sun."

- Hiccup talking about the Fireworms. The Fireworm is like the cockroach of the dragon world, that is, if a cockroach could superheat its skin to burn everything it touched. It also has traits from bees in that they create gel that's stored in honeycomb-like structures and have a queen.

Behavior
These dragons are often found in large groups. This makes them extremely dangerous. They are even remotely aggressive, occasionally clinging to potential enemies. Usually Fireworms make their homes in dark caverns. Fireworm Queens are very protective of their firecombs of gel and will chase down anything that tries to take it. Despite their aggressive nature, they seem to know if another dragon's fire is worn out, and are kind and sympathetic enough to reignite other dragons' firepower with their venom.

Appearance
Their appearence differs significantly between the average fireworm and the queen fireworm:

Average
Common Fireworms are about half the size of Terrible Terrors. They have dark gray scales with red skin underneath, or gray skin that turns red when heated; however it seems in Riders of Berk, they have orangish-brown scales. They also have five pairs of legs for a total of ten legs. They have fierce eyes that glow in the dark. They resemble lizards, with their wide heads and long bodies. When they heat, they glow white-red, and sometimes light their bodies on fire.

Queen
The queen of the fireworms (the Fireworm Queen) looks quite similar to your average fireworm, but she has some differences that make her outstand from the rest. For instance, while the common fireworm can fit in the palm of a hand, the queen is many times bigger, her size is comparable to that of a Monstrous Nightmare. She also posseses several protuberances in the back and front of her head that resemble a crown. The Queen was seen only at fireworm island so her original colour (the colour when not heated up) is unknown. It is  unknown if the queen even have an original colour.

Abilities
All fireworms can heat up their skin to a temperature of hotter than the Sun and being high enough that they can burn almost anything. While doing so they also generate a great amount of light, and sometimes, they even set themselves on fire. It is known that the closer two fireworms are to one another, the brighter they will shine.

Applying their body heat, Fireworm Queens have extremely powerful fire breaths that are twice as powerful as Night Furies', and are comparable with the Bewilderbeasts' ice blasts very unruly gaseous fire that spews out small fireworks. They also have strong prehensile tails that can pick up large objects over 5,000lbs or more. On top of that, they are able to stand on four legs and their tongue has a venom that has the ability to reignite the worn out fire of Monstrous Nightmares (and possibly other dragons). Fireworms can also produce some kind of gel that gives them their fire and they store in honeycomb-like containers. This same gel can give a Monstrous Nightmare back his fire.

In Book of Dragons
These dragons do not appear in the Book of Dragons short.

In Dragons: Riders/Defenders of Berk
When searching for the fabled Hamish Treasure, Hiccup, Astrid, Snotlout, Fishlegs, Ruffnut, Tuffnut, and their dragons find themselves trapped in a cave. While searching for a way out, they find a large, dark opening. Entering, they realize that the "floor" is moving. Toothless lights the room, and they find thousands of little Fireworms bustling about in a shallow pit. They find multiple pedestals in the heart of their nest, and the dragons try to frighten/fight the smaller reptiles off until the kids can find a way out.

They also make a small reappearance in "Gem of a Different Color", where Tuffnut tried to jump into a pit full of Fireworms while holding a Changewing egg which he still thought  was a "Stone of Good Fortune" thinking the stone won't let Fireworms burn him, only to be saved by Stormfly.

Fireworms are explored more thoroughly in "Race to Fireworm Island", where it was revealed that, like Fireworms, they have their very own island and nest, which is overseen by their mother, the Fireworm Queen. The reason behind their constant and extreme heat is also explained to be that they feed off firecombs, filled the very same gel that gives the Monstrous Nightmare its flaming ability. This is why they were given the name 'Flame-Eaters' by Bork the Bold.

Notable Fireworm Queens
The Fireworm Queen that chased Hiccup and Snotlout (see Race to Fireworm Island)

Trivia

 * It could be possible that the Fireworms recieved their name after one of Stoick's Monstrous Nightmares from the original novels.
 * They are extremely powerful in packs, as it is shown that all of the kids and the dragons together struggle to hold off a swarm of Fireworms.
 * Though they had already been discovered by Vikings, as Hiccup was easily able to identify them, their statistics have not been discovered yet (possibly due to the low danger rate they emit on their own).
 * In the Cartoon Network website, the Fireworms have no wings at all, but it is possible the images on the site are just concept arts instead of the final version of the images. However, there are two images: one of them has wings, and the other doesn't. They don't fly in the two Season 1 episodes they appear in (the first of which involving a situation that might have warranted their flight had they the capability), which seems to support the lack of wings. "Race To Fireworm Island" confirms beyond doubt the existence of wings.
 * It is possible that they are based off the Red-Hot Itchyworms, as they look similar and have very similar attributes.
 * In the episode, it is stated that the Fireworm's skin burns hotter than the sun. The Deadly Nadder's flame is supposed to burn with the heat of the sun, so logically touching a Fireworm should be hotter than being hit by a Deadly Nadder's flame, although it is likely they use a less intense heat normally.
 * Despite the Terrible Terrors being considered the smallest of all dragons, Fireworms are actually much smaller, and can be held in the palm pf your hand.
 * Fireworms and Monstrous Nightmares are both Stoker Class dragons, being able to set themselves on fire.
 * Bork the Bold originally called the Fireworms "Flame-eaters", but the name and the reason behind it faded from common knowledge.
 * It could be possible that the idea of Fireworms came from fireflies(their ability to fly), fire-ants(their biting exchanged with heating their skin) or bees (since they live in packs and have a queen and produce honeycombs replaced with firecombs).
 * The reasons why normal Fireworms are afraid of fire are unknown.
 * The closer they are to one another the brighter they glow.
 * Overall, mother lightly resembles the Yinglong like the Grapple Grounder, but Fireworm's features are more suiting than the Grounder; golden colored, unnaturally powerful (and hot), being generous and intelligent.