There are many reasons why a hive of native stingless bees will swarm, but they are all different to a honey bee swarm, which is for the purpose of colonisation.
The most common native bee swarms include Mating Swarms and Fighting Swarms. A mating swarm occurs when a new ('virgin') queen needs to mate - she lets surrounding drones know that she is looking for someone to mate with, which can attract hundreds of male bees.
Fighting swarms are an incredible phenomenon where a strong colony of native bees will find a weak colony to attack and take over. There can be thousands of bees swarming, and many dead bees. The strongest colony will win, so it is usually recommended to let nature take its course if this happens to your hive. Swarms can last anywhere from a couple of days to a couple of weeks. More information on native bee swarms can be found here.
3. Stingless Bees Make Honey
Stingless Bees can produce small quantities of a deliciously tangy honey, often called Sugarbag. It tastes of the Australian Bush - Citrus with a hint of Eucalyptus! Sugarbag is a rare treat, and is only harvested when it is safe for the hive to do so (leaving enough for the bees behind).
Research is currently being done on the medicinal properties of Sugarbag, and it is being indicated that it has extremely high levels of anti-microbial activity, possibly even more than the well known Manuka honey. Sugarbag is definitely not the sort of honey that you would spread onto your toast as a snack (aside from being expensive and rare, it is also very runny), but it tastes delicious drizzled on vanilla ice cream or yoghurt :)
4. Stingless Bees Make Propolis
European Honey Bees make their honey comb out of pure wax (hence its light colouring). They mix their wax with resins collected from trees to create a strong glue-like substance (called propolis) used to fix up gaps around the hive. The beekeepers often collect this material for its medicinal properties.
Native Stingless Bees make their entire hive out of propolis - this includes the honey and pollen pots (meaning that the resins infuse with the sugarbag). Propolis is also what gives stingless beehives their aromatic smell, which is similar to that of the Australian Bush. Some species of stingless bees make a 'doormat' of propolis outside their entrance, for them to wipe their feet on!
5. Stingless Bees can still Defend Themselves
Stingless bees may not be able to sting, but by no means are they defenceless. Over the years they have evolved to have other strategies of dealing with pests and intruders. Here are two native bee defence methods:
Native Bees can occasionally deliver a small nip with their mandibles, which isn't exactly painful, but is certainly annoying. This usually only happens if you disturb (open up) a defensive colony.
For pests like Small Hive Beetle (SHB), the bees will locate the insect and continually dab resin blobs onto it until it is covered. This process essentially mummifies the intruder, and the body gets incorporated into the hive structure.