The Meaning of Life, the Universe, and Everything.
There are certainly mods that add a great deal of mobs to the game to make environments more interesting- however, (In my opinion), many of these mods are over ambitious, don't go well with vanilla content, or are simply for older versions. This is a general idea for a mod that would add a new type of creature to the game that is both useful and adds life to the otherwise largely static environments of the Overworld. These Beetles would be about a quarter of a block in size, and would offer a means of farming otherwise unobtainable resources such as flowers and mushrooms, an easier means of obtaining dyes, new possibilities for brewing... and possible a new set of tools and armor. As always, I'd be more than happy to do graphic design for this mod, or for similar ones, and, quite frankly, have too much free time on my hands.
These relatively common creatures would be the regular sort of beetle you encounter- a small, skittish passive creature that can cling to the sides and undersides of blocks, and flies away a short distance if a player gets too near. They correspond to the sixteen dye colors, and, when killed, drop 0-2 of their dye color, and 0-1 Shell Fragments of their color. Like sheep, breeding colors together can result in a secondary color of beetle. (They can be bred with... rotten flesh? Maybe?) Anything with Bane of Arthropods would scare away any nearby beetles. Beetles could be hunted by foxes, bees, and possibly... cats? Maybe cats just play with them, because cats are adorable? They are as follows: Light Green Beetles are found in jungles and prairies. They're fairly common. Green Beetles are found in Covered forests and Taigas. They're somewhat slower. Yellow Beetles are found in jungles and prairies, especially around sunflowers. Orange Beetles are unique to Mesa plateaus. Red Beetles are found in flower forests, covered forests, and jungles. Blue Beetles are rather difficult to find, as they only spawn in flower forests, and occasionally in jungles. Light Blue Beetles are found in cold biomes. Cyan Beetles are only found near coasts. Brown Beetles are found in forests. They're more skittish than most beetles. Black Beetles are only found at night. White Beetles are unique to cold biomes, and are rather hard to find, partly thanks to their natural camoflauge. Light Grey Beetles are found in mountains. Grey Beetles are found in mountains. Purple Beetles are unique to swamps, and can go underwater to avoid players. Pink Beetles are unique to flower forests and jungles. Magenta Beetles are only found in jungles.
These variants of ordinary beetles look more or less identical to other beetles, save in that they have a flower or mushroom of some sort growing from them. When a player gets close, they burrow into the ground if on a soil block, and then only fly away if the player gets very close. They can be sheared for their flower and mushroom, which eventually grows back, allowing players to farm these otherwise irritatingly elusive resources. (Technically, I believe warped and crimson fungi can be farmed, for the record.) Flowery Yellow Beetles have a dandelion growing from them. Flowery Red Beetles have a poppy growing from them. Flowery Cyan Beetles have a cornflower growing from them. Flowery White Beetles have a daisy growing from them. Spotted Red Beetles have a red mushroom growing from them, and are found primarily in mushroom isles, as well as (rarely) in covered forests. Spotted Brown Beetles are similar to spotted red beetles. Spotted Crimson Beetles are a netherworld beetle that grows a crimson fungus on it. They're possibly hostile, dealing a light poison effect if startled? Spotted Warped Beetles are a netherworld beetle that grows a warped fungus on it. They maybe inflict a nausea effect if startled?
These rare beetles would be quite difficult to obtain- possibly, bottles with these beetles in them can (rarely) be found in woodland mansions or witch huts. Alternatively, a shiny Shell Fragment could be crafted by surrounding a shell fragment with eight ingots/gemstones. Shiny Grey Beetles are made of iron, and drop 0-3 ingots on death....Possibly iron golem themed? Shiny Gold Beetles are made of god, and drop 0-3 ingots on death. Possibly also found in Bastion Remnants? Glittering Diamond/Emerald Beetles are an ultra-rare type that drops 0-1 of its corresponding gemstone on death. Blue Glow Beetles are found in caves deep underground and in soul sand valleys- they only light up when clinging to a surface, casting caves in eerie blue light that vanishes as the player gets too close. Yellow Glow Beetles are found in the Netherworld. They drop glow stone dust on death.
Water Beetles ~ Coral themed beetles found underwater. They would drop coral.
Other Potential Additions
Some other things such a mod might include could be: Shell Fragments ~ Occasionally dropped by a beetle on death- applying a shell fragment to another beetle changes that beetle to the color of the fragment. Phase Shards/Phase Equipment ~ A shell fragment could be surrounded by eight Phantom Membrane to create a phase shard.These shards could be used to make an unusual armor set that would be slightly below iron in terms of durability. The Phase Armor would give a significant speed and jump boost, and would 'fracture' when it broke, dealing a large amount of damage to any nearby mobs. Craftable Elytra ~ Phase Shards could be used to craft elytra. Maybe. This might be really unbalanced, unless perhaps an eye of ender was necessary. Or something. Beetle Bottles ~ Try saying that five times fast! Glass bottles can be used to capture beetles, resulting in a 'Bottle of [Beetle Type]' These can then be released, ideal to start farming beetles for dye or other useful resources. Beetle Bottles can also be used in brewing. (I'm not entirely sure how, but it might be interesting.) Better Beetle Bottle ~ Combine nine beetle bottles to create a single Better Beetle Bottle, (And you thought the last one was hard to say.) You would get the other eight empty bottles back, but the resulting better beetle bottle would release nine beetles at once- ideal for distracting enemies. Potion of the Beetle Master ~ This potion would convert any nearby beetles into friendly entities that attack any hostiles near you in an incredibly distracting swarm. It would, of course, require beetles to brew. Potion of Levitation ~ While a levitation effect is already induced by shulkers, this potion could be made from certain beetles, and would cause you to levitate shortly before sustaining significant fall damage. Lord of Arthropods I-V ~ An enchantment applicable to equipment, and an opposite of Bane of Arthropods that would convert spiders, silverfish, endermite, and beetles into neutral entities. Wearing enough equipment with Lord of Arthropods would actually cause nearby spiders and beetles to attack other hostiles. Arthrokineticy I-V ~ A powerful enchantment, (And one that would probably be very difficult to program), that would allow you to control insects.While Lord of Arthropods would be applied to armor, this would be applied to tools and weapons. A weapon enchanted with Arthrokineticy would cause any nearby arthropods to attack whatever you're attacking- whereas a pickaxe would cause them to mine things for you, a scythe to harvest things for you, and so on and so forth. This would allow you to conserve durability... and better control your epic swarm of insectoid minions.
TLDR (Summary) ~ A (relatively) simple mod that adds a new mob to the game that both allows the farming of otherwise difficult to obtain ingredients, and adds more life and vibrance to otherwise drab areas of the Overworld; along with various new potions, equipment, and other stuff related to these insects.