When's the Last Time You Saw A Firefly with A Little Lantern?

When's the last time you saw a firefly with a little lantern?

If you really think about it, it seems like the glow of nature in the dark is fading away. Many people have never even seen a firefly in person -- indeed, fireflies are becoming less and less common. Less can not help but let a person sigh: read again "light luo small fan flapping firefly" and "capsule firefly ying snow" these ancient poem idiom, can we only imagine that picture, but can not have the real and immediate memory?

The fireflies are in the same predicament as most creatures -- habitat loss has severely affected their survival. But what you may not know is that nighttime light pollution is the second biggest threat to the global firefly population.

Light Pollution Silences fireflies

Artificial Light At Night (ALAN) has its own name in the academic world. With the continuous development of economy and increasingly bright lights, ALAN has become one of the global ecological problems. It is conservatively estimated that 23% of the land is suffering from some degree of nighttime lighting pollution. Before human beings did not use lights to light up the night sky, only the moon and stars and other celestial bodies, mainly fireflies can decorate the dark.

Now the convenient light brightens our lives, but the arsenic of my honey has never imagined that the ever-brighter light has brought disaster to the fireflies. Light pollution from excessive nighttime lighting is putting the insects at risk, according to a comprehensive assessment of firefly populations by 49 researchers from different countries.

The direct effect of light at night on fireflies is to reduce their activity rate. A comparison experiment in the field confirmed this conclusion -- a study in the Brazilian countryside found a significant reduction in firefly sightings after light exposure. Even when exposed to the lowest level of direct light (about 0.0438 lux at the full moon), local Photinus fireflies are only half as active as when they are not (FIG. 3). Moreover, the parallel experiment by adjusting the light intensity found that fireflies became more and more "shy" with the increase of light intensity, and the activity of fireflies in the strongest light group (Figure 1 below) under the influence of light was less than 10%.

The direct effect of light at night on fireflies is to reduce their activity rate. A comparison experiment in the field confirmed this conclusion -- a study in the Brazilian countryside found a significant reduction in firefly sightings after light exposure. Even when exposed to the lowest level of direct light (about 0.0438 lux at the full moon), local Photinus fireflies are only half as active as when they are not (FIG. 3). Moreover, the parallel experiment by adjusting the light intensity found that fireflies became more and more "shy" with the increase of light intensity, and the activity of fireflies in the strongest light group (Figure 1 below) under the influence of light was less than 10%.

In addition, light does not discriminate between males and females. A male firefly flashes a love signal, and if a female finds him, she flashes a specific frequency in response, indicating acceptance of the offer. Light pollution also changes the frequency of female flashes.

In the case of Photinus obscurellus, a female's normal response flash should consist of five patterns, but under intense red light, she emits only a lone flash. At this time, the love language is ineffective in both directions, and males and females can no longer understand each other's love words. This unique and beautiful way of courtship loses the effect it should have had for thousands of years, and the likely result is a dead end situation that cannot continue to reproduce.

How to reduce the effects of light pollution on fireflies?

As the situation of light pollution at night becomes more and more serious, Fireflyers International Network (FIN), an international firefly organization, has launched an initiative to minimize the negative impact of ALAN on fireflies by reducing unnecessary lights at night and transforming lighting equipment.

Fireflies are rarely found in cities, so they should not directly affect their populations. But a variety of intense light sources in a city, working together, can produce pollution called sky glow (one of the ALAN types). The sky glow is so widespread that it can illuminate even suburban areas, which in turn affect fireflies in the countryside.

In fact, the impact of sky glow can be reduced by simple modifications to the lighting facilities, such as adding a cover to the omni-directional light source or appropriately reducing the location of the light source, without affecting the lives of residents while minimizing the divergence of the top light.

For people living in suburbs or rural areas, there may be an ecological environment suitable for firefly survival. In this case, the light source in daily life can be changed to voice-controlled light or timing light, which can significantly reduce the direct impact of light on firefly. A more practical suggestion is to replace traditional light sources such as sodium mercury lamps with LED new energy lamps, which are more energy efficient and durable.

In addition to the economic advantages of lower energy consumption and longer lifespan, leds also have better ecological benefits because the wavelengths of traditional sodium mercury lamps attract nocturnal insects, such as moths. In contrast, LED lights had a smaller combined effect on nocturnal insects, and significantly fewer insects were attracted to them.

Humans are also victims of light pollution

The disturbance of light pollution to organisms is comprehensive and extensive. In addition to fireflies, other animals (such as moths, bats, birds, and bicreepers) and even plants can be adversely affected by excessive nighttime light. Of course, human beings are no exception, long-term light pollution will cause harm to people's sleep, mood, endocrine and other physiological and psychological activities.

As a part of nature, we, humans and animals alike, were not fully adapted to an era when the night sky was as glorious as day. In today's increasingly advanced technology, how to let those plants and animals that have been adapted to the dark life for millions of years can continue to live happily, is one of the problems we should consider when we coexist with nature.