Circle of Infestation

The Circle of Infestation is made up of foul followers who see to the importance of the grisly tasks carried out by insects at the end of natural life. Often revered as bad omens and given ominous nicknames such as Reavers or Reclaimers, these champions of the low set to work ushering in the final phase of existence-decomposition and reclamation. The public's fear is not wholly without reason-of all the established circles, the druids of this order have been the most frequent in abandoning their noble pursuit in the name of power. Still, while many have wielded their terrifying powers for self service, many more still honor their oath to complete their dirty work-welcomed or not. 

Credit where Credit is due - Subclass inspired by Jiggerton's Circle of the Swarm here on D&D Beyond. Our creations and functionally similar and yet wholly different. Check his out :D 

(D&D Beyond won't let me link his page :( still-give it a look)

Infestation

Starting at 2nd level, you have become a host for sickly, flesh and marrow eating larvae which you can inflict upon others. 

When you hit a creature with a melee attack, you can expend a use of your Wilshape feature as a bonus action to infest the target of your attack with burrowing larvae. The target must make a Dexterity saving throw against your Druid Spell Save DC. On a failure, a creature takes Piercing damage equal to your Druid level and becomes Infested for one minute by a number of larvae equal to your Proficiency Bonus. On a success, a creature takes half this damage and is not infested.

While Infested, a creature:

• Can not regain hit points
• Takes 1d4 Piercing damage at the start of its turn for each larvae it is Infested with
• Dies when it is reduced to 0 hit points
• May repeat this saving throw on its turn instead of performing one of its attacks. On a success, the target removes one larvae, which immediately dies. A creature with multiple attacks may repeat this saving throw once for each attack.

Undead creatures make all saving throws against this feature at disadvantage, while constructs, creatures with the regeneration feature, and creatures immune to the Grappled condition automatically succeed.

Sire of Swarms

Starting at 2nd level, when a creature Infested by you dies, a Swarm of Beetles bursts forth from its corpse.

When created in this way, a Swarm of Beetles has additional benefits:

• The swarm's hit point maximum is increased by your druid level
• The swarm adds you Proficiency Bonus to its damage rolls
• When you reach 10th level, the swarm becomes a Swarm of Flying Beetles, gaining a fly speed of 50 feet

On each of your turns, you can use a bonus action to mentally command any creature you made with this feature if the creature is within 60 feet of you (if you control multiple creatures, you can command any or all of them at the same time, issuing the same command to each one). You decide what action the creature will take and where it will move during its next turn, or you can issue a general command, such as to guard a particular chamber or corridor. If you issue no commands, the creature only defends itself against hostile creatures. Once given an order, the creature continues to follow it until its task is complete.

The swarm is under your control for a number of hours equal to half of your druid level, after which point it dies

Swarm Cloak

Starting at 6th level, while you are occupying the same space as one of your swarms, any critical hit against you becomes a normal hit.

Skittering Retreat

When you reach 10th level, in response to taking damage, you may use your reaction to halve the damage dealt to you, transforming into a Swarm of Flying Beetles in the process.

You may then move up to 50 feet to either an unoccupied space or a space occupied by one of your swarms. During this movement, you may freely pass through enemy and friendly spaces, fly, and do not provoke attacks of opportunity. If you occupied the same space as one of your swarms prior to this movement, they may expend their reaction to move to your new space, enjoying these benefits. Following this movement, you immediately regain your form.

Once you use this feature, you must finish a short or long rest before you can use it again.

Lord of the Swarm

Starting at 14th level, you always have the Insect Plague spell prepared, and it does not count against your number of prepared spells.

You may cast it once without expending a spell slot. When cast in this way, the spell gains the following benefit:

• When you cast the spell, you can choose unlimited creatures you can see to be unaffected by it
• You may use an Action on subsequent turns to move the spell up to 60 feet
• Your Flying Beetle Swarms gain a bonus to attack and damage rolls equal to your Wisdom modifier while they are within the spell's area
• You gain the benefits of Swarm Cloak while you are within the spell's area

Once you cast it in this way, you must finish a short or long rest before you can cast it in this way again.

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