Water and Humidity
The highest concentration of firefly species can be found in the world's warmest and wettest areas, specifically the tropical regions of Asia and South America. Some Asian species are actually fully aquatic, equipped with gills and feeding on underwater animals such as snails and slugs. Fireflies from all over the world live in or near standing water of all kinds, from huge swamps to small moist depressions.
Long Grasses
Fireflies are nocturnal insects and appreciate any source of shade or coolness. Since they spend most of the daytime on the ground, they use long grasses as a place to rest and hide from the sun. At night, the fireflies climb to the top of the grasses and signal for their mates from a higher, but still fairly safe, vantage point. If you would like to make your lawn more hospitable to fireflies, keep your grass long.
The Rainy Season
Although fireflies prefer a humid climate, they can also be found in arid regions. Even places with a dry climate have a rainy or wet season. Fireflies will flourish and breed during this time. Food can be scarce for fireflies in drier areas, but scientists have yet to determine the full extent of the firefly diet. Fireflies that live in dry regions might not eat at all, as their time is seasonal and often only lasts a few weeks.
Firefly Larvae
The lights of the fireflies are brightest during the mating season when they are trying to attract a mate. The larvae of fireflies are found in the same places as adults, with a few additions. Firefly young also like cool, dark places and standing water, but they can also be found in rotting wood and forest growth. Several tropical firefly species pupate under living leaves. Like their parents, firefly larvae are carnivorous.