Can you explain this contradiction?

You know that insects’ body temperature is dependent on the external temperature, right? It means that they can’t feel the temperature changes.

Recently the weather is getting freaking hot here. I notice some ants gathering around anything with water in my house: water cups, water containers, and even water fans. My parents explain that the ants are trying to cool themselves, lest they will die of the heat.

If ants can’t feel the temperature changes, why do they indulge in such behavior as if they know it is getting hot? Can anyone explain this contradiction?