Deathstroke was no chemist, but knowing how to deal with formic acid was simply one of a soldier's basic skills.
Formic acid was also called ant acid. Basically, every species of ant contained it, and ants were among the most widespread creatures on Earth, no less common than flies, mosquitoes, or cockroaches.
Mercenaries often had to carry out missions in rainforests or on vast grasslands, lying prone in bushes or clumps of grass for days at a time. In such places, some ants tended to be extremely unfriendly.
Generally speaking, ants were not aggressive toward humans, but there were exceptions, such as army ants, bullet ants, fire ants, and so on. Entering their territory or migration routes often invited frenzied attacks.
When they bit, they injected large amounts of formic acid into the wound, causing localized tissue necrosis. So if one insisted on saying ants were venomous, that would not be wrong.
A bullet ant bite hurt as if one had been shot, while a fire ant bite felt like being roasted alive. Their names had clearly been coined by people who had been bitten by them, and they were very fitting.
Even for a top mercenary like Deathstroke, his old armor had not been designed to defend against ants.
What if being bitten by certain ants left someone itching unbearably and affected their combat condition? Then solve the cause of the pain and itching—neutralize the formic acid the ants had injected into the wound, thereby relieving both.
Usually, washing the bite site with dilute ammonia or soapy water would do the trick. There might be no soapy water in the wilderness, but ammonia water was actually easy to find.
That was right: human urine. After being expelled and sealed away for a while, bacteria would break down the urea