Taken at night in Singapore.
Quote from en.wikipedia.org/wiki/Firefly
Lampyridae is a family of insects in the beetle order Coleoptera. They are winged beetles, and commonly called fireflies or lightning bugs for their conspicuous crepuscular use of bioluminescence to attract mates or prey. Fireflies produce a "cold light", with no infrared or ultraviolet frequencies. This chemically produced light from the lower abdomen may be yellow, green, or pale red, with wavelengths from 510 to 670 nanometers.
About 2,000 species of firefly are found in temperate and tropical environments. Many are in marshes or in wet, wooded areas where their larvae have abundant sources of food. These larvae emit light and often are called "glowworms", in particular, in Eurasia. In the Americas, "glow worm" also refers to the related Phengodidae. In many species, both male and female fireflies have the ability to fly, but in some species, females are flightless.
Tropical fireflies, in particular, in Southeast Asia, routinely synchronise their flashes among large groups. This phenomenon is explained as phase synchronization and spontaneous order. At night along river banks in the Malaysian jungles (the most notable ones found near Kuala Selangor), fireflies (kelip-kelip in the Malay language) synchronise their light emissions precisely. Current hypotheses about the causes of this behavior involve diet, social interaction, and altitude. In the Philippines, thousands of fireflies can be seen all year-round in the town of Donsol (called aninipot or totonbalagon in Bicol). In the United States, one of the most famous sightings of fireflies blinking in unison occurs annually near Elkmont, Tennessee in the Great Smoky Mountains during the first weeks of June. Congaree National Park in South Carolina is another host to this phenomenon.
Female Photuris fireflies are known for mimicking the mating flashes of other "lightning bugs" for the sole purpose of predation. Target males are attracted to what appears to be a suitable mate, and are then eaten. For this reason sometimes the Photuris species are referred to as "femme fatale fireflies."
Many fireflies do not produce light. Usually these species are diurnal, or day-flying, such as those in the genus Ellychnia. A few diurnal fireflies that inhabit primarily shadowy places, such as beneath tall plants or trees, are luminescent. One such genus is Lucidota. These fireflies use pheromones to signal mates. This is supported by the fact that some basal groups do not show bioluminescence and, rather, use chemical signaling. Phosphaenus hemipterus has photic organs, yet is a diurnal firefly and displays large antennae and small eyes. These traits strongly suggest pheromones are used for sexual selection, while photic organs are used for warning signals. In controlled experiments, males coming from downwind arrived at females first, thus male arrival was correlated with wind direction, indicating males' chemotaxis into a pheromone plume. Males were also found to be able to find females without the use of visual cues, when the sides of test Petri dishes were covered with black tape. This and the facts that females do not light up at night and males are diurnal point to the conclusion that sexual communication in P. hemipterus is entirely based on pheromones.