I can definitely see their stingers becoming lodged in the hull on occasion, perhaps not EVERY time though. Also, lets consider this from another direction: In order to assault deathmobiles, they could have corrosive stinger venom. Even if they can’t directly penetrate the hull, they could basically suicide ram the vehicle until a hole is melted in the hull by the fluids from their ruptured stingers.
We need some way of making them more threatening, because as of right now a survivor driving around in a bubble car with a single mounted gun and a lighter could exterminate a whole hive without ever being in any danger. Attacking a Bee Hive or Ant Mound should be a difficult, dangerous affair, with the bugs actively fighting back and seeking to obstruct you. It should probably require multiple NPCs as backup. I’m imagining it like this: https://www.youtube.com/watch?v=jXUYgMX3vuk