Insects’ teenage years are tough

(22 December 2017) Being a teenager is hard anyway, but if you think we humans are doing it tough at that age, then look at insects.
Each insect belongs to one of two groups: those with Complete Metamorphosis (like caterpillars, top-photo), and those with Incomplete Metamorphosis (photo of the cockroach).
Both kinds start with eggs laid by the mature insects. The creepy crawlers that come out of the eggs are called larvae in case of Complete Metamorphosis and nymphs in the other case. Most of those go through different stages when they grow, each time moulting their skins. They crawl out of the skin (called exoskeleton) to allow themselves to grow more. Normally they also develop new features in their new stage, for instance eyes or wings. Each stage is called an instar, counting from one up. Cockroaches can go up to 13 instars before reaching maturity.
For insects in the Incomplete Metamorphosis group this is the whole story: the adult insect is simply the last, and biggest, of all instars. Earwigs, katydids, crickets, dragonflies, bugs and cockroaches belong in this group.
85% of all insects are more sophisticated, by going through Complete Metamorphosis. Larvae of these insects have different names, like larva, grub, maggot and caterpillar. The final instar of the larva turns into a pupa. After a short while a completely different looking insect emerges from that, referred to as ‘imago’. In this group we find ants, flies, lacewings, beetles, cicadas, butterflies and moths.
The photo shows the caterpillar of the Batwing Gum Moth, the biggest caterpillar in Australia. This one was about 12 centimeters long. The second photo shows a cockroach which has just left its former exoskeleton, enabling it to grow further.
Both sightings were recorded last Wednesday in MacDonald National Park, and despite around 200 previous night walks we had never seen any of these before. Nature keeps surprising!
And, just in case you are not that thrilled to learn about cockroaches, only very few come into houses. Worldwide and also in Australia the American and German cockroaches are the most common house-visitors. Where, nice detail, the German cockroach has a different name in one country in the world: in Germany it is called a Russian cockroach.

Both photos taken with 60 mm macro-lens, Canon 700D camera, tripod, no flash, f/11.