One of the hottest chiles in the world (some say the hottest), Scotch bonnets are irregularly shaped with color ranging in shades of green, yellow, orange, and red. This small chile looks very much like a habanero, which is sold in most supermarkets and which is a fine substitute. Some people claim to pick up a hint of sweetness through the fiery punch.
You can substitute habanero chiles.
Choose chiles that are shiny and firm pods with strong, uniform color. They should feel dense and heavy for their size; good examples of even the very smallest ones will feel heavier. Avoid chiles that are flaccid, wrinkled, bruised, blemished, or discolored.
Use care when handling Scotch bonnets: wear gloves, remove the seeds and veins, and consider using less to start with.
Store Scotch bonnets in the crisper drawer in the refrigerator for up to a week.