M18

The M18 Colored Smoke Grenade is a US Army grenade used as a ground-to-ground or ground-to-air signaling device, a target or landing zone marking device, or a screening device for unit movements. It is not designated the "AN-M18" but "M18." It can be seen repeatedly in the film Apocalypse Now 1979. It was discovered in Vietnam that the green smoke drove away swarming bees.