Hi S.,
You've got already a lot of good ideas. Just one more, go to the website of Oriental trading.com, you will find a lot for Ladybug party.
They do have several options for kids crafts including "ladybug bell ornaments" just in time for Christmas?
Garden pot craft kit... cute as a bug photo frame, foam ladybug craft kits, bracelet craft kit, bug catcherbox kit AND paint your own ceramic ladybug bank... I think all kids enjoy painting and glueing and all the crafts.
Even being December maybe a small moonwalk?, something really small, you may be able to get a very good deal because is not season and if it si early and sunny with the kids well covered would be good. Check the weather, a day like today or even a little colder is perfect for it.
If money is not a question here you can even rent a small tent with "walls" and put the bouncer there.
Hope you have a great party!
M.