Question: What is the biggest ant?
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Ants are one of the youngest insect groups, evolving around the same time as flowering plants at the end of the Mesozoic Era. Most likely they evolved from ground-based wasps. The largest modern species are African Driver ants, but the largest ever was the 50million-year-old Titanomyrma gigantea, with females around the size of a hummingbird (6cm).
Australia has a large number of ant species (940 compared to Europe's 180) and the largest are the Myrmecia or bulldog ants.
Genetic tests show this group split from all other ants 100 million years ago, making them 24million years older than T-Rex. They were also one of the first Australian species discovered and scientifically described, with Joseph Banks encountering them in 1770. Banks recorded: "Of insects there were but few sorts, and among them only the ants were troublesome to us."
Some 18 years later, the First Fleet's Watkin Tench noted: "Of ants, there are several sorts, one of which bites very severely." The bulldog ant is considered the most primitive, which explains the various differences to most ants. Not only are they large (some around 4cm) and long legged, they are long lived, with some workers living well over two years.
They are solitary hunters, roaming about in search of prey such as other ants, bees, wasps, caterpillars and even small frogs and lizards. These they despatch with their enormous mandibles, which can give a nasty bite. They also are unable to follow chemical trails, instead using their powerful vision to hunt prey and locate threats.
The feature that makes them dangerous to humans, and goes back to their wasp-ancestors, is the enormous sting they carry. Unique among ants, this sting can measure 6mm, and is connected to a large venom gland. On a 4-point pain index, the bulldog sting ranks between 2 and 3. The sting also has no barb, so unlike bees (and again, just like wasps), they do not lose their sting when they attack, allowing them to repeatedly stab with the weapon.
This makes them dangerous to humans with a low tolerance to ant venom, and one survey found that between 1980 and 1999 there were six deaths due to stings. That means there are more recorded deaths in Australia by ants than from snakes and jellyfish combined.
Response by: Phil Hore, National Dinosaur Museum
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