We know about the very hungry caterpillar who goes through a beautiful transformation after munching through a garden deli of delights. But do we know about the many other insect species that undergo this process of metamorphosis?
In fact, more than 80 per cent of insect species and possibly around 60 per cent of all animals undergo metamorphosis.
The inside story
Metamorphosis is the process where an animal changes in its life growth with dramatic physical differences. Starting with an egg stage, it changes in a series of developments to become an adult. In the adult phase, many develop brand new organs such as wings or lungs. While many of us know that caterpillars transform to become amazing moths and butterflies, we often forget and see them as pests to be always eradicated.
So, here’s to supporting moths, butterflies and many other insect species that metamorphosise!
There are two types of metamorphosis - complete and incomplete. Complete metamorphosis consists of four life stages, with incomplete metamorphosis consisting of three.
Certain insects, such as butterflies, moths, bees, wasps, ants, and beetles, experience complete metamorphosis. This process involves each stage of the insect's life cycle having a distinct change in appearance from the preceding and succeeding stages. As a result, the egg hatches into a larva, which then enters a pupa stage before maturing into an adult.
The larvae of insects that undergo complete metamorphosis look entirely different from their adult counterparts. They may live in different habitats and have different food sources than the adults. Larvae may be soft and worm-like, but they have a voracious appetite! During this stage, they moult their skin several times due to their rapid growth. The larvae are inactive and do not feed when they are inside their cocoons. During this stage, the insects develop more bodily components such as internal organs, legs and wings. The pupal stage starts when cocoons are formed around the larvae, which can last from four days to several months. These insects undergo complete metamorphosis.
Shining the spotlight on some overlooked insect pollinators that metamorphosis:
Wasps
Wasps are often overlooked as essential contributors to ecosystems and have specific roles in improving biodiversity. They are known to act as pollinators, and a very important role is pest control. Wasps make up a diverse range of insects, with more than 112,000 species in over 70 families according to the Cleveland Museum of Natural History The Australian Museum states that there are over 12,000 species in this country.
Scientific studies have confirmed that certain plants have evolved to attract and use wasps for successful reproduction. It is worth noting that around 98.5 per cent of wasps have been identified as solitary non-stinging types around the globe as stated by the website PennState Extension: Wasps-Beneficial and Pollinators.
To keep active, wasps need to maintain a high metabolism, which requires a diet of high energy foods. This includes sugar in nectar and proteins from other insects. The flowers that attract wasps usually contain high quantities of nectar in shallow spaces that allow wasps to drink. Despite being less effective at pollinating than bees, wasps are often mistaken for them. How to differentiate between bees and wasps? Wasps have a lower pointed abdomen and a narrow waist, and they are less hairy.
All wasps undergo complete metamorphosis, which includes four stages in their lifecycle. This process is the same for both solitary and social wasp species. In Spring, queen wasps emerge from hibernation and begin to build nests for themselves. They usually choose a warm spot and can fly up to 70 kilometres searching for the perfect nest site
The queen wasp then builds a honeycomb-like cell structure out of wood fibre. With the help of the wasp’s saliva and paper-like material from leaves, single eggs are deposited into each cell, which hatches into a larva in five to eight days. The queen wasps then go searching for insects to feed their larvae. The larvae rapidly grow as they shed their skin multiple times during development. After shedding during the first stage, worker wasps (male wasps) forage for more food such as nectar and pollen.
As new eggs are deposited by the queen wasp, the nest of the wasp grows, and new cells are added to accommodate them. After a few weeks, the larvae spin the cocoon around themselves and then enter the pupal stage. It takes around eight to 18 days before an adult wasp emerges from the pupal stage.
Beetles
There are over 30,000 known species of beetles in Australia according to the Australian Museum, and scientists say many more are yet to be discovered . Beetles have a head, thorax, abdomen, and six legs. Some horned beetles have extensions on their head. The middle section of the beetle is called the thorax. Beetles have a forewing called an elytron, which is a hard shell that protects the thin wings underneath, enabling beetles to fly. Some beetles can trap moisture under their wings. The abdomen is where the organs for digestion and reproduction are located. They breathe through tiny holes on the sides of the body called spiracles.
Beetles play an important role in maintaining the stability of ecosystems. They are involved with nutrient recycling by transporting freshly deposited wastes into soils. Beetles are also thought to be very effective pollinators – their abilities evolving for about 250 million years! Beetles are considered to be among the first insects that pollinated flowering plants. Many beetles are hairy which allows pollen grains to stick to them which can then be transferred to other plants.
A beetle’s reproductive season typically starts sometime between Spring and Autumn. After they mate, female beetles return to the habitat they constructed and lay their eggs. The colour and the number of eggs laid depend on the types of species of the beetles. Most of the beetle species lay their eggs near adequate food sources such as rotting wood, dead leaves, and animal faeces. Most eggs will hatch in a matter of days.
Grasshoppers
Grasshoppers are flying insects that belong to the order Orthoptera and go through incomplete metamorphosis. It is estimated there are more than 10,000species of grasshoppers globally. Australia has about 500 native grasshopper species according to the Business Queensland website.
The majority of grasshoppers are herbivores. They begin their lives as eggs which are laid hidden in soil. The female then sprays a sticky substance on the eggs to form an egg pod which contains between 10 to 300 eggs. During Autumn and Winter the eggs remain in the soil. When the weather becomes warmer during spring or summer, the eggs hatch and emerge as nymphs. Nymphs are tiny versions of the adult grasshoppers and do not have wings. They then progress through a series of moults to become adult grasshoppers. Moulting is the process by which the animal sheds the skin as the animal matures. In the instance of grasshopper metamorphosis, the nymph undergoes a series of six stages of moulting before becoming an adult. Grasshoppers remain nymphs for six weeks before becoming adults. Once the nymph enters 25 to 30 days of transforming into an adult, wings begin to develop. Adult grasshoppers have more mobility and the ability to hunt and escape from predators.
Crickets
Crickets are found in a variety of colours such as brown, green, red and black, depending on their species. They are medium-sized to large insects. Cricket’ hind legs are bigger and stronger than the other pair. They have rounded heads, antennae that are long and thin, and their wings bend down on the sides of their body. Crickets also undergo incomplete metamorphosis. A cricket begins its life in an egg. After 14 days, they become nymphs and break out of their eggs. Just like grasshoppers, cricket nymphs do not have wings. To grow, a nymph must shed its hard exoskeleton. The new exoskeleton is milky white and after a few hours it hardens. After a month, wings will start developing in a cricket nymph. When a cricket becomes an adult, its wings are fully developed and it has only two goals – hunting for food and mating. Crickets will try to attract females and once mating has happened, a female will try to find appropriate places to lay her eggs.
Article written by Zeerak Ayaz
Header photo by Suzanne D. Williams on Unsplash