Auckland Museum's experts examine our world in a five-part series. Today: insects, with entomology curator John Early
KEY POINTS:
The world of insects is a wonderful lesson in the diversity and adaptations you can find in just one group of living animals. There are more species of insects than all other animals put together and you can find them in just about every different habitat on the earth.
Renowned naturalist Charles Darwin studied insects when he was a university student, often spending more time hunting for beetles than studying and preparing for his exams.
OUR SEARCH
Sand scarab beetle (Pericpotus truncatus)
This is common at sandy beaches but, like a lot of our insects, it hides away so most people don't even know it's there unless they know where to look.
The native sand scarab beetle is a large chunky beetle built like a small tank. The biggest ones are about 3cm long and are shiny black or dark brown. Their short stocky legs are perfect for pushing through and burrowing in sand.
A hot sandy beach is a hard place for an insect to live and so the adult beetles come out at night. Take a torch and head into the dunes after dark.
Sometimes you can find dead ones on the sand in the day time; these are beetles that didn't find somewhere to shelter from the scorching sun by daybreak.
It's usually much easier to find their larvae. Look underneath driftwood that's partially buried in the sand and looks as though it's been there for a long time. The big fleshy larvae have a whitish body and ginger to brown coloured head. The ginger coloured dots along their sides are spiracles, the openings to their breathing system. They sit curled up into a C-shape in little holes under the decaying driftwood which they eat. When you disturb them, they become very active and burrow down into the sand.
Don't collect live larvae or beetles, but take a photograph or make a drawing of them, and remember to put the driftwood back in the same position as you found it to let them re-establish their homes. It's okay to collect a beetle if you find it dead.
Fortunately, sand scarabs are not endangered and are common on sandy beaches all around New Zealand.
* * *
Native seashore earwig (Anisolabis littorea)
The second insect is the native seashore earwig, which you might also find while you're hunting for the sand scarab. You can find them under driftwood and stranded seaweed on sandy and rocky beaches above the high tide line.
This lovely dark brown earwig is a little bigger and sturdier than the common European species that you find in your garden. They feed on small insects and other creatures which they attack at speed and crush with their forceps (pincers) at the tail end.
Take a closer look at the forceps and you will be able to tell what sex your earwig is. In females, they are symmetrical so the right and left ones are identical in size and shape, but males have the right one more strongly curved than the left. See if you can find both sexes.
Seashore earwigs are common all around the New Zealand coast and its offshore islands.
* * *
Common bag moth or case moth (Liothula omnivora)
Look for these hanging on twigs and branches of trees and shrubs, particularly manuka, kanuka and macrocarpa in your garden, parks and in the bush.
The "omnivora" part of their name indicates that they are omnivorous which means they feed on a wide variety of plants so you'll find them on other kinds of trees too.
Inside the case is the caterpillar. It makes the case from very tough silk and decorates it with bark, twigs and leaves to provide camouflage.
You can easily keep these as pets. With patience and a bit of luck you might see the caterpillar pop its head and legs out of the case and start walking along the twig while carrying its case.
When disturbed, they immediately retreat and shut the mouth of the case.
The Maori name for this insect is kopi, meaning "shut", because most of the time the cases are closed.
Try feeding them different kinds of plants to see what species they will eat.
Although the case is tough and gives great protection from birds, it doesn't stop them being attacked by parasitic flies.
Many of the bags you find will be empty, the caterpillar having been killed long ago.
Despite this, the bag moth is common throughout New Zealand because it can feed on a variety of plants.
* Illustrations from Powell's Native Animals of New Zealand, which is published by Auckland Museum.
John Early - Auckland Museum natural history manager and curator of entomology
As a kid I spurned sports. I preferred to spend solitary hours with books or puddling around in ponds and streams, excavating clay banks to find the lairs of trapdoor spiders.
I also liked observing birds and insects in the garden, being entranced by life in miniature on a moss-covered rock and marvelling at the beauty and diversity of the natural world.
In the 1970s, I studied zoology and botany at the University of Canterbury. I abandoned dreams of becoming a marine biologist a la Jacques Cousteau when serendipitous post-graduate research introduced me to the fascinating world of the insects, in particular the tiny parasitic wasps which are still my main research focus.
