Fireflies

Viewed from afar, the flickering and flashing of glowing fireflies can light up a dark night's sky. This quality, however, is for much more than mere entertainment, as the emission of light serves several functions. Firefly flashes are a source of protection, communication, and self-presentation. But the adults' glow is also used by some species for deceptive purposes.

The enzyme-driven chemical reaction that allows fireflies to produce light begins shortly after birth. Although the light might seem to attract the attention of predators, it may actually serve to deter attacks, as the enzymes that produce light in the larvae have a bitter and undesirable taste. Throughout the course of evolution, predators learned to associate the glow with this aversive flavor in nascent fireflies. The emission of light, then, serves as a warning signal and source of protection for the glowing larvae. Because of the light's protective function, fireflies' ability to glow does not disappear over the course of maturation.

[Page 384]In fact, many species of firefly evolved to retain the ability to produce light even as adults. As a result, the emission of light by adult fireflies now does more than discourage predator attacks; through evolutionary development and individual maturation, glowing serves multiple functions.

Male fireflies battle for female mates and use their glow in the fight. The females assess size and strength as males display dominance and superiority. Among the characteristics on exhibition during the mating rituals is a firefly's flashing ability. Male fireflies vying for the attention of potential female mates use their light as a form of communication and courtship. Males use varying, complex light patterns as a form of signaling. Males vary the time-delay within flash patterns. Ranging from multiple, fast pulses to fewer, long-lasting flashes, these flash patterns are species specific. The displayed light pattern allows females of some species to locate partners of their own kind and decipher their mating intentions. Females can then use their own pattern of flashes to return responses to their courting counterparts.

While the standards that females use to assess mate viability are yet to be fully understood, scientists believe that males' light signals may also serve as a determining factor for females in mate selection. That is to say, these complicated flashing patterns may allow females to discern which male will provide the most food to help nourish their eggs and afford them the greatest reproductive success. Packages of protein injected with the male's sperm during the mating process serve as sustenance for pregnant females. These bundles are referred to as “nuptial gifts” and are vital for a female firefly's survival during the procreation and birthing processes. Scientists believe that among the complicated patterns of glowing pulses are some indications from the males about their ability to provide this nourishment. In this way, the flash communication assists female fireflies in the imperative task of correctly identifying a well-providing partner. Furthermore, females return light displays to signal their interest to males they judge to be viable partners.

While the majority of female response flash signals are genuine communications of mating interest, at times the flash pattern is a deceptive one. Some species of female fireflies reply to courting males with light patterns that are intended to mislead males. These females then use the deceived males in order to increase their own chances of survival.

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