Butterflies and moths have one of the most fascinating life cycles on the planet. These insects go through four stages of life: egg, larva, pupa, and adult. As they progress through these stages, they transform from caterpillars to stunning winged insects during a process called metamorphosis.
There are over 17,000 different species of butterflies in the world. The exact details of each species’ life cycle vary. For instance, some have longer lifespans or different mating rituals. The amount of time it takes for a butterfly egg to hatch or for a fully-formed butterfly to emerge from its chrysalis also varies between species. But, in general, their life cycles follow the same pattern from birth to death.
Butterfly Mating Rituals
The mating rituals of butterflies can be beautiful to watch. Scientists have only studied the rituals of a few different species but have noted some general patterns.
Female butterflies are ready to mate almost as soon as they emerge from their chrysalides. The University of Minnesota’s Monarch Lab points out that, for monarch butterflies at least, the males become sexually mature about 4-5 days after emergence.
In many cases, it’s the male butterflies that initiate the mating ritual. In a terrific piece over at livescience.com, Joseph Castro explains that male butterflies seek out mates in one of two ways. Depending on their species, males are either perchers or patrollers. Perchers sit and wait for a female to flutter by. Patrollers fly around, actively searching for a mate. Males use visual cues to determine which females would be good mates. The colours and patterns on a butterfly’s wings are key in locating mates of the species.
Once a male spots a potential mate, he begins his courtship ritual. He starts by flying close to the female, often just behind or above her. Once in place, he releases pheromones to attract the female. He may also perform a courtship dance: a specific flight pattern that varies from species to species. While this is beautiful to watch, it does serve a purpose: it helps spread the pheromones onto the female’s antennae, making the male’s bid for courtship more powerful.
The female may decide to fly away if the patterns on the male’s wings aren’t a good match for her. Or, she may engage in the courtship dance as well, or just choose to mate with the male.
Some species have different rituals. A male monarch, for instance, might just grab a suitable female out of the air, in an “aerial takedown,” and initiate mating on the ground. However they get to that point, butterflies mate by facing in opposite directions. With their abdomens touching, the male butterfly uses his “clasper” to hold tightly to the female while he passes sperm to her reproductive tract.
Female butterflies carefully choose where to deposit their eggs. Once hatched, butterfly larvae don’t move very much. The eggs need to gestate on a larval food source so that the young caterpillars have easy access to food.
A detailed piece at ThoughtCo explains that some species of butterflies lay their eggs in clusters while others scatter them one-by-one on different host plants. As the eggs leave the female’s body, they are fertilized by the sperm left during mating. For most species, it takes about 1-2 weeks for the eggs to hatch.
Larvae are about the size of ants when they hatch. In this stage of life, they mainly just stay on the same plant they hatched onto and eat. They start by consuming their eggshell and then begin feeding on the host plant.
As they grow, their exoskeletons become too small and they molt. Each stage between molting is called an “instar.” Immediately after hatching caterpillars are in their first instar. After molting for the first time, they move into their second instar. They continue eating and pooping until it’s time to molt again. Typically, caterpillars have five instars. It is during the fifth instar that caterpillars prepare to pupate.
Once a caterpillar is ready to pupate (go through metamorphosis to become a butterfly), it often wanders off its host plant, looking for a safe spot where it can form its chrysalis.
At the Gardens with Wings website, Regina Cutter Edwards perfectly explains what happens inside the chrysalis:
The insect’s body basically is liquefied by digestive fluids and the body is restructured using specialized formative cells. This process is called histogenesis, in which undifferentiated cells are used to build different body tissues.
Butterflies don’t always emerge from their chrysalides as soon as metamorphosis is complete. They may instead remain at rest until something triggers them to emerge. As the piece at ThoughtCo points out, triggers include changes in light or temperature as well as chemical or hormonal signals.
After emerging from the chrysalis, a butterfly often perches upside down for a few hours. During this time, the wings dry and are pumped full of hemolymph (the equivalent of blood in invertebrates). As well, the waste products from metamorphosis are discharged. Once this process is complete, the adult butterfly is free to fly off to feed on nectar and to find a mate, so that the butterfly life cycle can continue.
Once they reach the adult stage, some butterflies–like coppers and small blues–will only live for a few days. Others, such as monarchs, may live for 6-12 months.
The life cycle of butterflies is dramatic and fascinating. It is often part of the curriculum in elementary schools, allowing children to become familiar with the wonder of metamorphosis. But, it isn’t difficult to watch that life cycle unfold in your own backyard. All you need to do is plant a butterfly garden that provides food sources for both larvae and adult butterflies. Add in a few other things to make butterflies feel welcome, such as stones to bask on and puddles to soak up nutrients from. With that oasis awaiting them, you may very well have a front-row seat for viewing the butterfly life cycle.