Rekindled Trauma

Kill it With Fire. Your entomophobia causes you to lash out with burning hate when facing insects.
After casting any spell that causes one or more insects or insect-like creatures to receive damage, you may spend your reaction to deal an additional 1d8 +2 fire damage to all creatures damaged by your spell.

You can use this reaction a number of times per day equal to your Wisdom Modifier.

In addition, you always have the Fireball spell prepared. It counts as a druid spell for you. Once per Long Rest, you can cast it without expending a spell slot.