Once after long professional journeys in the past, I came home to Lahore deeply jetlagged. Awakening that warm night, I woozily wondered if this was Rio de Janeiro or Los Angeles – but then something of deep reassurance happened. On my bed net, I saw a faint flash of tiny, greenish light about two feet from my nose: it was a jugnu or a firefly inside our bedroom. “Ahh this can only be Lahore, at home in the month of May”, I thought, turning over and falling into blissfully secure sleep.

Fireflies are the jewels of our childhood memories, inside those treasure chests of happy history we store in the attics of our mind. Our lullabies still refer to jugnus as harbingers of sleep and sweet dreams, and I have seen many a cynical adult melt into a bleary-eyed memory when the mention of jugnus comes up.

I locate the firefly in my early childhood memories of pristine Mangla, in district Jhelum, where I grew up surrounded by tropical thorn forest. A wild child, shy of humans, wandering in garden edges, scrub slopes, and grasslands of the Salt Range, my world was focused on the insects, plants and birds that abounded in great variety.

Such a constitution is usually an early morning person, whose nighttime signals bodily tiredness after a day spent outdoors in perpetual observation and movement. In that twilight of the mind, the jugnu is a final imprint prior to sleep. This is how I remember jugnus, between the interface of wakefulness and sleep, on the stormy nights of May when the weather turns to summer heat.

Well, it turns out that the twilight flickering of fireflies as a harbinger of summer is ingrained globally, with over 2,000 different firefly species spread over the world. Children everywhere cup hands and peek through fingers to watch them glow, wondering how these fascinating insects produce light. Biologists call this their unique cultural significance.

There are firefly stories in many cultures even though we think of them as a secret that is our very own. Japanese legends tell of fireflies, or hotaru, as the souls of the dead, specifically the spirits of warriors who fell in battle. Native American Apache legend relates a story in which the trickster fox tries to steal fire from the firefly village. After setting his own tail on fire, firefly tells fox he would never to able to use fire again. In ancient Amazonian mythology, firefly light came from the gods to provide hope and guidance.

That magical glow called bioluminescence is explained in the language of chemistry and serves to amplify this marvel. Luciferase is the spark that makes the magic, an enzyme whose name should not be confused with the devil. Lucifer comes from the Latin lucis, or light, and ferre, meaning to carry. Luciferase is the enzyme that brings light when oxygen enters the rear end of the firefly, the location of the light-producing organ.

Each type of firefly flashes in a pattern and colour unique to its species, used as a tantalising marker to be seen by others of its clan. It is this courtship display that marks these soft beetles as an iconic species. The oceans have many deep inhabitants with bioluminescence that glow eerily in waters devoid of light. But the land dweller’s glow is distinctive to fireflies.

Our jugnus give flash signals, but it is not clear whether these are the males signalling courtship or whether the females are also part of a flash dialogue in which they give a light response to their males. Many fireflies engage with each other in this way. In only two places in the world, there’s a phenomenon known as simultaneous bioluminescence. That means that all the fireflies in the area synchronize their flashes, so they all light up at exactly the same time, repeatedly, all night long. The places where this can be seen are in Southeast Asia and the Great Smoky Mountains National Park in the US.

For all their charisma, fireflies ask for wet places to grow. They like patches of grass and waterside thickets, and in some areas mangroves, in which they lay their eggs below the soil, and hibernate during the cold, sometimes for a few years. When they do emerge in spring, they feed on other insects, slugs and snails, and are themselves not edible for other predators such as owls or frogs because they carry a noxious steroid that repels eating.

Yet, as this insect lives vividly in our imagination, its distribution is less understood and protected. In 2018, a global species specialist group for fireflies has been formed and they collected current information from scientists the world over. Yes, Pakistan, too, has its firefly researchers, some based in the University of Faisalabad, whose paper on these insects was presented at the world firefly conference in Malaysia. The suspicion is that the loss of their preferred habitat, artificial light at nighttime and the use of pesticides is a real problem for fireflies.

This month, during our final walk at night, we counted six jugnus in little thickets of un-mown grass and verges of empty houses. We marvelled at their flashing magic, and figuratively put them for safety into the treasure chests of happy memory, safe for deep reassurance.

— The writer is a Lahore-based ecologist