Sorry about your duck! I've heard the scorpions are bad this year. They feed on other pests so people use bug control to help. If you have crickets, ants or roaches, scorpions eat those so get rid of them if you can.
Unfortunately if you have bark, leaves or detritus in your yard they can hide there. Even your yard decorations, the kids toys, bird feeders, etc.
Also, keep an eye out around any water sources. I'm sure you've got a pool or a pond with ducks. Any hiding places near that I would check regularly.
Chickens supposedly eat scorpions. I've seen mine with lizards, don't know about the scorpions.
Use a caulk to fill all cracks and crevices in and outside. Look around spigots, windows, doorways, anywhere you might have gaps. We used this foam stuff that set rather quickly.
Your other choice is squish with a boot. A park ranger once told me people THINK they don't have scorpions, they just don't know they do. Good luck!