Let’s first address the question of pain. There is a simple way to test this: let something sting you.Entomologist Justin Schmidt has famously allowed a lot of insects to sting him in the name of science. He has developed his own pain index, with excruciating descriptions of how each sting feels.

Unlucky people in Central and South America will probably agree with Schmidt that the most painful sting is that of the bullet ant. Even its name is an allusion to the agony of being shot.However, the tarantula hawk wasp actually delivers the most venom per sting: a generous 2.5mg. Nevertheless, Schmidt describes it as "essentially non-toxic, just painful".In contrast, the Maricopa harvester ant may have the most potent venom among stinging insects. Each ant has only a little venom, but they live in colonies of up to 10,000 and will swarm any threat, so can be pretty dangerous.This highlights a key point about stingers: they do not just cause pain, they can also pose a threat to life and limb. Scorpions, in particular, are famous for their dangerous stings.

Scorpions possess some of the world’s most fearsome-looking stings: a barb and venom sacs located in the final segment of the tail, the "telson".However, scorpion expert Lorenzo Prendini of the American Museum of Natural History says that only around 20 of the 2000 known species are considered "medically important", meaning they pose a threat to human life.All but one of these dangerous scorpions belong to a family called the Buthidae, the members of which are spread around the globe from Mexico to Brazil, and from sub-Saharan Africa to India. However, the worst species seem to have clustered into a global hotspot."There are many highly venomous species in North Africa and the Middle East," says Prendini. "Most of the fatalities are attributed to Leiurus quinquestriatus and various species of Androctonus, especially A. australis and A. crassicauda."L. quinquestriatus is also known as the "deathstalker", while Androctonus means "man slayer". These names are no exaggeration.

A. australis is a hardy creature that, rather than digging burrows, shelters in crevices – including the walls of rural properties. It can grow to 4 in (10cm) long, and its venom contains powerful toxins that target the nervous system."The effect of scorpion envenomation depends both on the virulence of the toxins contained in the venom – with respect to their action at the cellular level – and the amount of venom injected," says Prendini."Therefore, a larger species with less virulent toxins in the venom, but capable of injecting a greater quantity of venom, like A. australis or Parabuthus granulatus, is potentially more ‘deadly’ than a smaller species with more virulent toxins but capable of injecting less, like Leiurus quinquestriatus."Most healthy adults will survive a scorpion sting, but only if they have access to the right medical facilities, including anti-venom."Most fatalities due to scorpion envenomation occur in young children, the elderly or infirm," says Prendini. "Most stings occur in rural areas [with] poor communities living in close proximity to scorpion habitat."Partly because most scorpion-related deaths happen in remote places, the records are not very reliable. The same is true of the deadliest stingers in the ocean.

Jellyfish and their relatives release projectiles to capture prey and defend themselves. These "nematocysts" are specialised cell structures that function like tiny harpoons when fired. Some deliver an additional toxic payload when they embed themselves in flesh, primarily to slow down fast-swimming prey such as fish.Of the 2000 species of jellyfish known to science, only 10-15 are considered a threat to human life.However, their relatives the box jellyfish – which actually belong to a different group, despite their confusingly similar name – are more likely to be dangerous.The largest box jellyfish is the sea wasp or Australian box jelly (Chironex fleckeri), which weighs in at up to 2.2lb (1kg). Sporting multiple tentacles each 10ft (3m) long and capable of delivering thousands of toxic barbs, its powerful venom acts on muscle and nerve tissues.

"Far and above, C. fleckeri has been responsible for most fatalities in Australia, and other species of Chironex are responsible elsewhere," says "jellyfish guru" Lisa-Ann Gershwin of Australia’s federal science agency CSIRO.In particular, if you measure deadly stings by how quickly they can kill, C. fleckeri leads the assault."C. fleckeri is considered the world’s most venomous animal," says Gershwin. "[Its victims are] stone-cold dead in as little as 2 minutes. That’s not a few in that little [time], that’s often.""It kills by locking the heart in a contracted state," adds Gershwin. "Once that happens, resuscitation is very unlikely: you can’t compress a compressed object. So the safety is all about avoiding the sting then early CPR."The other name that looms in discussions of deadly box jellyfish is the Irukandji.

Until recently, there was thought to be just one Irukandji jellyfish, named after the native Australians living along the north-eastern coastline where the sting was first recorded in the 1950s. But experts now recognise around 25 species of jellyfish in the order Carybdeida, all of which share an unnerving stinging ability and are found around the world.The smallest’s bell measures just 1cm tall, but they have a tentacle on each corner that can measure 100 times their body length. The venom expelled from cells on both their tentacles and bell disrupts the normal processes essential to life.Unlike other jellyfish stings, the onset of symptoms is not immediate. "Irukandji syndrome" begins to present after 20-30 minutes and includes back pain, nausea, muscles spasms, a sense of impending doom, and the possibility of a heart attack from extremely high blood pressure."Of the Irukandjis, Carukia barnesi is by far the commonest stinger – it swarms," says Gershwin. "But Malo kingi, Alatina alata, and Morbakka fenneri are the ones that result in life support because of the severe hypertension their stings can cause."Compared to C. fleckeri, the Irukandjis are "far more potent drop-for-drop," but provided timely medical treatment is sought they are less likely to kill, says Gershwin.That said, Irukandji stings leave no mark, so fatal encounters with these invisible killers may have been under-reported historically. Meanwhile, 68 people have died due to C. fleckeri in Australian waters since 1883.However, these days not many people die, thanks to education about the seasonal appearance of dangerous jellies and improved medical treatment. If we want to find stinging animals that kill on a large scale, we have to step back onto land.

Asian giant hornets are the largest stinging insects in the world, and they have earned the nickname "hornets from hell".In Japan, 30-50 people die every year due to giant hornet stings, which break down flesh and overload organs. In Ankang, China in 2013, 41 deaths in three months were attributed to a seasonal surge in hornet numbers.These seem, at face value at least, to be larger numbers than any of the other species. But that statement comes with a big caveat: deaths from scorpions and box jellyfish are poorly recorded. That means the comparison is unfair.Arguably, the deadliest stingers actually belong to animals we possibly could not live without. Schmidt says the species that pose the greatest risk – or at least should command the most respect – are some of the most familiar: honeybees.

These bees all belong to the genus Apis. Many people in Europe and North America are familiar with European honeybees (A. mellifera), while people in Asia are more likely to encounter giant honeybees (A. dorsata)."Honeybees A. mellifera and A. dorsata have potent venom, lots of it, thousands of attackers and an ‘attitude’," says Schmidt.For most people, a single honeybee sting merely results in localised pain and swelling. However, when one honeybee stings you, it releases an alarm pheromone that calls its fellow workers to join the attack.Still, it takes a lot of stings to kill you. Schmidt says that in most cases, "a person would not be at serious toxic risk with fewer than 500 stings." Anyone on the receiving end of a few hundred honeybee stings would surely feel pretty sorry for themselves, but most of us would survive it.Nevertheless, there are several factors that make honeybees the deadliest stingers.

The first is that honeybees have a global distribution thanks to our thirst for honey. This relationship also means that people come into frequent contact with them, increasing the chances of stings.The second issue is that some honeybees are particularly aggressive.Domestic honeybees have been bred to be docile, but the wild honeybees of Africa are much more likely to attack predators en masse. In the 20th Century they were introduced to South America and have since spread north, where they are known as "killer bees".Killer bees have killed several hundred people over the decades. However, they only attack if they decide you pose a threat to their hive. Leave them alone, and they will almost certainly let you be.

Finally, a single sting can prove fatal – if you have an allergic reaction to it."Anaphylaxis" happens when a person’s immune system over-reacts to an allergen, triggering rapid swelling that leads to tissue damage and difficulty breathing. Really extreme reactions, known as anaphylactic shock, can cause a person to asphyxiate, especially if they have a pre-existing condition such as asthma. Stings from ants, hornets and jellyfish can trigger such a reaction but bee stings are more often recorded.Fortunately, anaphylaxis is not common. In the UK less than 3 people die every year as a result of bee stings, while in the US the figure is around 55.Still, it shows that when it comes to stingers, the devil you know could be the worst.