Have a separate path for druids. Alternatively could be feat based.
1. Animal empathy works on vermin (bypassing mind immunity) but not animals. Probably should continue to work on magical beasts (some spider models are magical beasts).
2. Wildshape into vermin instead of animals, could just be a reskin of the existing forms.
3. Instead of elemental shape change into a swarm of insects, drop the attack/damage towards zero but give them an aura that deals level scaled poison (or piercing) damage similar to Aura of Fire. Add in no-collision with other PCs/NPCs like Wraith Stride.\
4. Poison-themed cantrip, could be damaging like Flare or could work like Blades of Fire but deal poison damage instead.
Inspired from Child of Winter (and related vermin feat-line) in 3.5, swarm druid in Pathfinder and 4E, and some of the more insect-based spellcasting in D&D for druids. Still reveres and lives in harmony with nature but a less "Bambi-esk" aesthetic.