Insects: did you know?

by User Not Found | Jan 07, 2016

Did you know that insects account for more than 75 per cent of all animalInsects species?

They generally have legs, wings and a body consisting of three parts (head, thorax and abdomen). Many insects undergo body changes during their lifetime—eggs, grubs, and then adults. Moths go through a caterpillar stage, which looks nothing like the adult moth. So insects can be very interesting animals to try to identify correctly. Centipedes and millipedes are not technically insects, nor are spiders, worms or snails.

There are probably more than 160,000 insect species in Australia and more than 1.5 million types of insects in the world. In Australia there are hundreds of types of mosquitoes, more than 1500 different types of honey bees, and 20,000 types of beetles.

Many New Zealand insects have their nearest relatives in Australia as Australian insects have been flying to New Zealand for millions of years. These include the Bogong moth. But some do not breed well nor survive for many generations in New Zealand.

Some names of insects are very descriptive—Christmas beetle, vinegar fly, elm beetle, zebra caterpillar, praying mantis, borer and bed bug. Some common names do not even sound like insects—ladybird, silverfish, water boatman, tick.

Tropical climates on continents such as South America support huge numbers of insects of tremendous variety.

Helpful insects

Without bees, the fruit trees and crops brought from Europe to Australia and New Zealand would not have grown properly. Butterflies and many flies are also important to help pollinate crops, and ants are very helpful in seed dispersal.

Ladybirds were introduced to control aphids on roses and vegetable crops such as cabbages. More recently introduced, dung beetles are great for reducing cow pats in paddocks, so that flies don’t breed in this rich source of undigested food and potential soil nutrients. Silkworms, which are the caterpillar stage of the silk moth, make silk which can be used to make beautiful cloth.

Some insects are useful for bait when fishing. A few insects can be eaten. Indigenous Australians eat the plump wichetty (witjjuti) grub, honey ants and Bogong moths, and huhu grubs are a traditional Maori food snack.

Birds, fish, reptiles, some marsupials (echidnas) and amphibians (frogs and toads) eat insects, which form an essential part of their diet. Some insects live with one particular animal species e.g. bat flies in New Zealand. These bat flies are unique small, wingless, spider-like creatures that live in the roosts of short-tailed bats.

Insect pests

Fruit flies, locusts and weevils are pests as they can destroy important food crops. But most insects are not harmful.

Some insects actually harm each other—wasps can feed on eggs from other insects, e.g. Australasian green shield bug eggs are harmed by wasps.

Humans need to be wary, as some insects cause a nasty bite or sting, e.g. European wasps, mosquitoes, bull ants, March flies and sand flies. And some people can have a serious allergic reaction to insect bites. For this reason never try to handle insects.

Observing insect activity

It is easy to observe insect activity in your garden. Use a magnifying glass and carefully look at any ants and flies. Some insects have very good camouflage—moths often adopt the colour of their host plant leaves.

Signs of insect activity may not be obvious if they are attacking the roots of the plant, but look more carefully at:

  • Leaves – spots, discoloured, curled, chewed

  • Fruits and vegetables – holes, colour change, scabs, rotting

  • Nuts – fail to form properly, discoloured at fruit stage 

  • Flowers– chewed, fail to form properly

  • Trees  - insects tunnel into the trunk 

Open the lid of your compost bin and, without touching them, check for insects (flies, ants etc.) and other animal activity.

Ants often live in holes in the ground or in brickwork, and some insects feed on grass and clovers.

Listen - some insects make a lot of noise. Listen in the garden or at the beach on a summer day. Bees buzz, mosquitoes whine. Some insects rub their wings together, some tap their wings on the ground and some ‘sing’, like cicadas, which can be extremely loud.

Creature chef - making ‘insects’ from food

  • On a plate use half cherry tomatoes or radishes to make ‘ladybirds’ adding currants to mimic their black dots, and don’t forget their tiny legs

  • Very realistic looking giant ‘ants’ can be formed from three cherries, using the cherry stalks as their legs

  • Peas or currants can be lined up to look like caterpillars

  • Butterfly and moth shapes can be made from snow peas, or empty pea pods

Take some photos before you eat your creatures. 

Insects and insecticides

Look around the supermarket at the number of products marketed to kill off insects. Do you use a fly spray or a mosquito repellent? Do you treat your cat or dog for fleas? Careful use of these products can be necessary at times, but excessive spraying can upset the biological balance and harm useful insects and other animals.

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