February 6, 2025, 9:42 am | Read time: 3 minutes
Is this ant peeing on me right now? That’s what some people ask themselves when they come into contact with the little insects. This is because it is not uncommon for ants to squirt a drop of burning liquid when they come into contact with humans. But why do they do this, and can insects even “pee”? PETBOOK editor and biologist Saskia Schneider answers these questions.
“As a child, ants used to pee on me when I was hiking,” a colleague told me recently. Is that really “wee-wee”? Others also remember how ants left excrement on their hands or legs, and depending on the species, this also caused a strong burning sensation. But why do ants do this? And is it really a kind of urine?
Can Ants Pee?
While mammals excrete urine and feces separately, many other animals do not have this distinction. This is also the case with ants. Like all insects, ants excrete a mixture that may include both liquid and solid components.
When an ant ingests food, it first passes through a long gullet into the crop, which is located in the abdomen of the animal. Ants can store food here and regurgitate it when required. This allows them to collect sugary liquids to feed their nestmates later, for example. 1
The portion of food that the ant itself needs to live reaches the stomach. This is where the food is mainly digested. The waste products accumulate in the rectal bladder and are then expelled through an opening at the end of the abdomen. Ants, therefore, expel a type of mushy waste rather than urine.
Also interesting: Ants can also hold grudges and may even seek revenge
Ants Conduct Their Business in the Nest, Not on Humans
Unlike honey bees, ants do not do their business outside the colony. At least we know from black ants that they usually stay at home when they need to relieve themselves. The toilets are located in the corners of the nests, as a study found in 2015. As a human, you will, therefore, rarely see an ant “doing its business.”
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Why Do Ants Spray Liquid on Humans?
But what’s the story behind the liquid that ants leave on the hands or legs of people walking through the forest? This is actually a defensive behavior. Red wood ants, in particular, show it – and not just when you pick them up. If the animals feel threatened, they stretch their butts forward – and spray formic acid, which is highly corrosive. As a result, the area usually starts to itch or burn. A good strategy to keep enemies at bay. 2
The formic acid is stored in the venom sac. Like the rectal bladder, it ends at the tip of the abdomen. To humans, this might appear as though the ants are actually urinating.