Fire

As a hazard

Has a destructive capability against anything flammable close to it and may expand to large extensions if left unattended.

Animals or Colonists

Caught on fire will become momentarily disabled by panic and attempt to extinguish their fire, while also wander into unsafe open areas where they might be vulnerable to attacks.

Interiors

Which reach higher temperatures (~235C/455F/508K), will burn with every flammable that is inside the room, and an orange haze effect will appear.

Objects

Caught on fire will take DOT (damage over time). The damage taken value will depends on the flammability of its material.

As a tool or weapon

Countermeasure against Infestations

Infestations are difficult to clear, especially when spread through multiple (mined out) caves.

An effective method is to equip a colonist with an incendiary launcher or Molotov cocktails and attack the hives one at a time. Without hives, insects will no longer be hostile.

Should one of your caves have power conduits running through all the area and completely sealed with roof, they could be used to spread the fire by closing the caves with walls and then simply shoot at a conduit to ignite. Insects will collapse and eventually die of burns or heatstroke, hives will ignite if the temperature reaches threshold.