Q.Is there an insecticide safe for use in moss gardens
I’m starting a moss lawn but I have ants, spiders, and palmetto bugs all over my yard.

Here are some links for you.
Neem Oil can be used.
Spiders are generally a benefit to the garden, so maybe they can stay!
https://www.gardeningknowhow.com/ornamental/foliage/moss/growing-moss-gardens.htm
https://www.gardeningknowhow.com/plant-problems/pests/insects/spider-garden-pests.htm
https://www.gardeningknowhow.com/plant-problems/pests/insects/get-rid-of-ants.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm