Realistic Bees

Realistic Bees is a mod which attempts to make bee behaviour more realistic without adding new items or objects to the game. Bees are 25% of their normal size. To make bees a little less uncommon, the mod also adds a config value (by default 9) which defines the extra amount of bees that spawn after each natural bee spawn. The bee hive can also hold more bees than Minecraft's default, changed from 3 to 20.

Hives can also fill themselves with new bees. When enabled in the config, a hive that is full of honey and still has space uses it up to release a baby bee. Breeding with flowers still works as well.

More bees means a hive fills up with honey a lot faster, so it's possible to require more nectar per honey level. Bees can also be made immune to campfire damage.

On 1.21.1 and newer versions, it is possible to use this mod server-side only. Players without the mod installed will still see the smaller bees.

It also works the other way around. With 'clientSideBeeSizeFallback' enabled in the config, you'll see the smaller bees on servers that don't have the mod installed. Only the server is able to change the hitbox though, so in that case it stays at the vanilla size.

All available config options:

beeSizeModifier default 0.25, min 0.01, max 5.0
This value determines the size of a bee. By default 0.25, which means they are 1/4th of their vanilla size. Set to 1.0 to disable the different bee size feature.

clientSideBeeSizeFallback default false
When enabled, bees on a server without the mod are made smaller on your screen only, using 'beeSizeModifier'. Their hitbox stays vanilla size there. Servers with the mod and singleplayer are unaffected, they change the actual bee size.

extraBeeSpawnsPerBee default 9, min 0, max 50
In order to make bees a little more common. Whenever a bee naturally spawns, the mod spawns an additional 'extraBeeSpawnsPerBee' bees.

beeHiveBeeSpace default 20, min 0, max 50
How many bees should be able to enter the hive in total. Minecraft's default is 3, but bees are a lot smaller so there should be more space.

preventBeeSuffocationDamage default true
The smaller (baby) bees can sometimes do something unexpected with their AI and get suffocation damage. Preventing this damage fixes them disappearing.

preventBeeCampfireDamage default false
Smaller bees fly closer to a campfire placed below their hive and can get burned by it. When enabled, bees take no damage from campfires.

nectarDeliveriesPerHoneyLevel default 1, min 1, max 20
How many nectar deliveries it takes on average to raise a hive's honey level by one. Minecraft's default is 1, but with more bees per hive the honey fills up a lot faster.

hivesRepopulateFromFullHoney default false
When enabled, a hive that fills up with honey and still has space uses up the honey to release a new baby bee.

Tiny bees! --or bigger. Depending on the beeSizeModifier config:

You may freely use this mod in any modpack, as long as the download remains hosted within the CurseForge or Modrinth ecosystem.

Serilum.com contains an overview and more information on all mods available.

Comments are disabled as I'm unable to keep track of them across so many separate mod pages.
For issues, ideas, suggestions or anything else there is the Github repo. Thanks!