How should I store this moon spell without attracting bugs?

I’d keep the dry pieces and remove the fresh strawberry and honey. Those are the parts most likely to attract insects or spoil, and sealing them in a jar can trap moisture. You could compost them and keep the dried ingredients in a clean, fully dry container.

If the physical ingredients matter to you, a small dry jar is a simple option for the salt and dried flowers. You could also write the intention on a slip of paper and store it with them, then let the perishable bits go. That keeps the reminder without trying to preserve food.

Paraffin wax can be used as decoration on the outside of a jar, but I wouldn’t count on it to make a damp mixture safe or airtight. Keep the contents dry, and don’t put hot wax near the shell or any flammable material.