There are many substances that hurt when injected under the skin or applied to an open wound, but don’t cause pain when applied to healthy skin.
It hurts to get stung by bees, wasps, and ants, but they’re injecting their venom under the skin via a stinger. OTOH, if I gathered their venom and just gently applied it to the surface of my skin, would it cause pain?
Just the venom from a single bee, ant or wasp? Maybe not hurt but possibley a skin reaction like.a rash. A larger amount may blister your skin or maybe have health benifts.
“Venom Skin Care: Does It Work? | Shape” https://www.shape.com/lifestyle/beauty-style/should-you-be-putting-venom-your-skin
Sure. I’m envisioning an insect that experiences the defensive equivalent of premature ejaculation.
So that’s considered defensive now? 
Ant venom is formic acid. I presume a large quantity could burn.