There are fourteen different types of enemies/creatures (colloquially called "mobs") in Bee Swarm Simulator.
Other than ants, the most frequently occurring mob is the Rhino Beetle and there are five of them in the game. The least frequently occurring mob is the Stump Snail respawning in 96 hours (4 days) or 81 hours and 36 minutes (if you have a Gifted Vicious Bee) upon defeat.
You can't fight the mobs yourself; only your bees can. One method for defeating mobs that works reliably for any mob which is defending a field (basically everything other than the King Beetle, Tunnel Bear, Ants, the Cave Monsters, Stick Bug, and Rogue Vicious Bee) is to jump continuously. It is one of the Glitches where when jumping, mobs will freeze and not attack which lead to your bees thinking the mob isn't a threat and not attack it. You do have to make sure your bees "know" to attack a mob before starting to jump - if the mob hasn't started attacking you, your bees might not recognize it as a threat.
Before the 2/1/2019 update, rewards from defeating any mob was sent to the player's inventory right when the mob is killed. After the update, the mobs drop a ring of tokens around it instead. (Battle Points don't spawn as a token). Other players can't steal tokens dropped by the mob if this mob isn't spawned by them. The tokens can be collected by a Token Link.
Mobs have levels that are shown next to their label. If your bees are a lower level than the mob they're attacking, they can miss.
Daylight Saving Time will affect the respawn time of the Snail, King Beetle, and Tunnel Bear.
Use Baby Love in mobs and bosses to get more and better rewards.