It's all based on a very fundamental mathematical law: if you increase the size of something, the volume increases with the third power while the surface area increases with the second power. An insect twice as large would be 8x as heavy and need 8x as much oxygen but 4x as much surface area.

That's also the reason why insects are as strong as they are. The strength of a muscle scales primarily with the cross section area of it, which again scales with the second power. So if you'd increase the weight of an ant by a factor 10,000,000 (e.g. 5mg to 50kg), the expected strength would increase by 10,000,000^(2/3) ≈ 46,400. If it could lift 10x it's weight at the original size, it could now only lift about 4.6% of it's weight

maybe once I have money for hobbies, but I really want to make oxygen rich terrariums, and selectively breed tarantulas to see if I can make them larger.

No because you’re likely too big (no offense) :(

I think insects have little holes all over their bodies, in which air gets inside by itself through some physics shenanigans. It doesn’t need to be actively sucked in like with lungs, it just happens because they’re so small.

This method doesn’t scale up though since if you’re bigger, you need more air, and having little holes all over your body won’t cut it. Thats when you know you need lungs, and that’s why you don’t see insects the size of a dog these days (thankfully).

There used to be times in the Earth’s history (Carboniferous) where the air’s composition was different though, and since it had more oxygen in it, insects could grow a lot larger.

Yeah, and if you pluck a chicken, it will be a human, because it's featherless and stands on two legs.

Which is why you don't see cat sized insects roaming around, I live next to a tarantula trail and some of them fuckers get BIG.

The bees were on a different lower down roof from the main roof (which is the one that burned). The article notes that bee wax melts at 70C and they didn't see any of that under the hives, so they know temperatures stayed below that. So the bees were likely only exposed to some smoke and maybe some slightly elevated temperatures.

Put simply smoke doesn't have to be hot. Smoke is just unburnt fuel caused by a process called offgassing (solid turning to a gas).

An example of cooled down smoke is a fire that starts in a well sealed room. It burns through as much fuel as possible, and while the solids are hot they turn into gas, however, due to a lack of oxygen, you don't necessarily see combustion. So then the fire snuffs itself out and what you are left with is a cooling smoke.

So let's say that the fire is on an upper floor. Heat goes up, cold goes down. So as smoke travels through a building it cools, and may eventually sink towards the ground or a lower level (this can be especially possible in a building as large as a cathedral) smoke sinks and interacts with bees at a "manageable temperature".

Tldr: smoke isn't always hot. The bees are happy.

In the original Jurassic Park novel by Michael Crichton, one of the animals they've cloned are these giant dragonflies. Its only one line in the book (Tim, one if the kids, sees one fly by and recalls reading about them) but it caught my attention as just straight impossible. I remember thinking, "Unless you're somehow controlling the oxygen level of the air around this entire island, there's no way that bug can't breathe."

To be fair, while bugs and other insects don't have lungs, some arthropods do. The differences among arthropods, insects and bugs aren't exactly common knowledge.

It's funny that this is biology in 4th grade and half the people here are shocked

Not just bees, it's true of all insects.

Consequently, the amount of oxygen in the air determines how big bugs can grow. Get too big, and the oxygen can't diffuse into the body fast enough. This even shows up in the fossil records, with larger bugs being found alongside evidence of eras that had more oxygen in the atmosphere.

Pedant here. They absolutely do have circulatory systems. They have what's known as an open circulatory system, whereas we have a closed circulatory system.