Crazy ants may sound like a Flappy Bird spin-off, but in fact this species of ant is slowly taking over Texas, thanks in part to their ability to neutralise the venom of fire ants.
The red imported fire ant, an invasive species introduced to the USA in the 1930s, has a fearsome bite that causes painful red irritations in humans and is used to kill other insects. Their venom contains various alkaloids, which can lead to allergic reactions in some cases.
Whilst most ant species are unable to displace the fire ants, crazy ants can detoxify their venom, the fire ants’ most powerful weapon. They do this using formic acid, which they produce and rub on themselves whenever they are affected by venom.
Researchers found that preventing ants producing formic acid by coating them in nail polish led to venom killing around half of the ants, compared to just 2% when the ants could produce the acid.
Thanks to this acid defence, in 93% of the cases where fire ants and crazy ants are competing for the same food, the crazy ants will be successful. They can even oust fire ants from their nests, giving the crazy ants a ready-made home to enjoy.
Unfortunately, whilst fire ants can leave their mark with a painful bite, they tend to stay in their nests and leave humans undisturbed. Crazy ants, on the other hand, will nest in anything available, including cars or fuse boxes, where they can short-circuit electronics.
Having first arrived in Texas from South America in 2002, crazy ants have spread throughout the state, causing damages to wildlife and livestock, and annoyance to residents. Thankfully, it should take a while for the crazy ant to completely take over the USA, as they can only spread at a rate of around 200m a year, although this can be accelerated if transported by humans, for example by accidentally hitching a ride in a car.
Crazy ants aren’t the only ants to use formic acid, whose name comes from the Latin formica, meaning ant. Some ants spray or inject formic acid as a form of defence, while others even use it as a herbicide. In the Amazon, ‘devil’s gardens’, named because locals believe they house evil spirits, are areas containing only lemon ant trees. Lemon ants inject formic acid into the leaves of other trees in the area, leading to the leaves dying. The ants can cultivate their preferred trees over areas up to 1,300m2, with colonies of over 3 million worker ants.