Blacklight bulbs are not to be confused with blacklight blue (BLB) ones. While they’re named similarly, and both give off UVA light, they have very different uses. Blacklight bulbs (often referred to as BL368 or BL350) are the ones you will see used in bug zappers in shops and kitchens, as the bugs are attracted to the UV light.
These bulbs commonly come in opaque white tubes – either straight or turned into more compact shapes. They emit a mixture of ultraviolet and visible light and will appear to glow a luminous blue colour when in operation.