Animal stories: Fireflies
Fireflies are small blinking insects that light up only at night. They are actually beetles that have common names like lightning bug and glowworm.
Fireflies are mostly black with two red spots on the head cove. The wing covers and head covers are lined in yellow.
They have six jointed legs, two antennae, compound eyes, a head, thorax, and abdomen.
Different types of fireflies vary according to the colour of flashes, how quickly they flash and how long the flashes last. In the evening, the last abdominal segment of the fireflies glows a bright yellow-green colour. They can control their glowing effect.
Male fireflies flash about every five seconds whereas females flash about every two seconds. Fireflies do not bite or carry diseases, they have always been a source of fascination for people.
Fireflies feed on other insects, insect larvae, earthworms and snails. They are carnivores and eats other fireflies also. Larvae of fireflies capture small prey, such as snails, worms, and mites. They inject their prey with a powerful acidic juice like spiders. The immature larvae will then suck out the dissolved body tissue. They sometimes scavenge dead snails, worms and similar organic matter.
Fireflies generally live underwater and are found around ponds, streams and ditches. Many species are also found in warm and dry areas. Most firefly larvae are found in rotting wood or other forest litter or on the edges of streams and ponds. Adult fireflies are found in the same general habitats as their larvae.
Fireflies start their life cycles as fertilised eggs. Female fireflies lay eggs slightly under the soil. The eggs hatch in four weeks. The larvae, once hatched, begin to feed until fall. The larva eats a lot. Fireflies remain in the immature larval stage for one or two years, building up ‘mud houses’ to protect themselves. After several weeks of feeding, they grow into pupa. Then after 1 to 2.5 weeks, an adult firefly emerges. For the next three weeks or so, their only work are to eat, sleep, and make more fireflies.
How do they glow
The light produced by fireflies is called bioluminescence. It is due to a chemical reaction that occurs in specialised light-emitting organs, usually on the lower abdomen. Although other insects can produce light, fireflies are the only insects that can flash their light on and off. Even the eggs and larvae of some firefly species glow. That’s where the name ‘glowworm’ comes from.
To make light, a firefly’s brain sends a signal to the light organ in its abdomen, where the light-producing chemical reactions occur. It is discovered that the process also involves a gas called nitric oxide. It’s this gas that operates the insect’s on-off switch.