Parents who set up a sandbox as a place for their kids to play may also unknowingly be setting up the perfect environment for insects to nest and build colonies. Instead of reaching for chemical pesticides to keep your sandbox insect-free, search your pantry. Generously sprinkle cinnamon all over the sandbox and rake it through the sand. Cinnamon is a natural insect deterrent, and it smells great. If you need a lot of cinnamon for your extra-large sandbox, look for generic brands or inexpensive bulk containers at your local warehouse club store.