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INSECTS

 

LOWLAND RAINFOREST INSECTS

 

* The Daintree has a very high diversity of rainforest insects

* They are the main leaf eaters in the lowland rainforest

* Insects are very important decomposers of wood

* They use fascinating camouflage strategies

* Distinctive colony ants live in the lowland rainforest

* There is a high diversity of wasps

 

Lowland rainforest insect life is the most diverse in Australia. Evidence of this can readily be seen at various scientific research sites such as the Daintree Discovery Centre which is part of the Australian Supersite Network. Many leaves show distinct signs of insect damage due to caterpillars of moths and butterflies, grasshoppers, crickets, Katydids and stick insects.

 

BEETLES

Insects, in particular beetles, are very important for decomposition and a large range of these can be found in the rainforest. 

Look closely at dead branches and tree trunks and you will find various holes of different sizes. The largest are often covered by a pyramid of sawdust and created by the Auger beetle Bostrichidae.  Smaller holes may be caused by the powder post beetle Ambrosia. And where a Cycad is maturing, species of weevils can be seen pollinating the cones. 

Many beetle larvae living in rotting wood produce large cream colored larvae that attract serious predators like the black and white Striped Possum. When the tree dies and falls to the ground feral pigs and bandicoots are also attracted by the chance of a tasty morsel. 

Some of the strangest looking beetles are those that have their eyes set in long stalks, located in the front of their head - for instance the Brentidae beetle. Another particularly interesting specimen is the Rhinoceros beetle. Most often seen during the wet season, the males have an elaborate and distinctive ‘horn-like’ structure on their forehead. 

You might also keep a look out for some of our ‘cryptic’ camouflage experts. The best example being the spiny cricket. It is 100mm long and covered in small green spines. It has very long antennae and particularly long legs. 

Spiny crickets can sometimes be seen sitting on the side of a tree trunk, in full view but their excellent camouflage means they can be hard to see. As part of its effective defense mechanism the spiny cricket bites a vertical channel in the bark in which it rests it's tummy, with legs extended backward and antennae forward to minimize its chances of being detected. 

Another master of camouflage is the tropical Caddis fly larvae. It builds it's own house from silk and decorates it with moss. The Caddis often looks like a small curved ice cream cone during the day when draws it's house tightly around it. Hiding, but in full view!! 

If you walk along one of the elevated walkways at the Discovery Centre you will come across a number of tall thin palms – some of them growing within easy reach of the platform. Take a moment to look at the at the base of the crown-shaft – particularly its structure (the smooth bit at the end of the frond). Here you will find a cream colored inflorescence about the size of a basketball comprised of re-curving strands. Along these strands are hundreds of small flowers and on them, the insect variety is magnified! 

As you walk around keep an eye out for strange ‘baggy’ brown lumps on the side of small trees. This may be the feeding site of the larvae of a spectacular beetle called the Longicorn Beetle. They sometimes use the trunk of the Bumpy Satin ash and when they vacate the hole, a small black ant takes over and builds up a colony that often remains for the life of the tree. These ants play an important role in preventing growths and helping to stop vines from colonizing the bark.

 

ANTS

There are many species of ant in the forest but the most common is the green weaver ant Oncyphilla. They were first noted by the naturalists who accompanied James Cook on his voyage up the east coast of Australia. However, it was a long time after that, that their nest building behavior was recorded. 

The ants swarm over the end of a branch and then pull the leaves together using chains of their bodies. Then the larvae are brought to the site and their silk glands stimulated. This material then forms a water-proof join. Once leaves start to die in the nest it is abandoned and a new nest is built.

 

 

WASPS

A feature of the lowland forest is the variety of its wasps – quite apart from the common mud nester and paper wasps. Each of the 40 species of figs in the Daintree has its own unique species of wasp to pollinate the special flowers inside the flower structure (Syncarpium). 

Gall wasps are also common and are responsible for the strange bumps and pegs seen on the upper surface of leaves. These structures are called ‘galls’ and contain a developing wasp larvae. The adult wasp lays an egg on the surface of a developing leaf. After the larvae hatches it starts feeding and the saliva of the larvae reacts with the growth hormone circulating in the leaf to form a hollow vertical structure in which the larvae develops, away from the attention of predators. 

 

BUTTERFLIES 

There are many colourful butterflies about the Daintree rainforest – triangles, leafwings, swallow-tails, sword-tails, cruisers, jezabels, blues and others.  The sunny edges of rainforest where shrubs are in flower often attract butterflies in numbers, particularly where the introduced lantana invades the perimeter. Here butterflies visit flower after flower, systematically searching for nectar. 

Like some of the colourful birds though, bright colours of many butterflies blend with the rainforest. Most butterflies are unobtrusive, flying only in bright sunny weather. The huge and beautiful Ulysses Butterfly however, is obvious, and often seen about the warm lowland rainforests of the Daintree. Brilliant metallic blue wings resemble an intense blue flashing light as the butterfly flies rapidly about open spaces against a background of green foliage. Often symbolised in promotional material in the tourism industry, it is as evocative to these northern rainforests as the Southern Cassowary or the Fan Palm. 

You may also be fortunate enough to see the large green, gold and black male Birdwing butterfly about the rainforest edges or clearings. With a slower, more relaxed flight than the Ulysses, it resembles a large leaf aloft on the breeze. The female is sombre in black and white with touches of yellow and red. With a wingspan of about 20 centimetres she is Australia’s largest butterfly. 

'Butterflies' extract from "Daintree - Jewel of Tropical North Queensland" by Lloyd Nielsen, reproduced with kind permission

 

 

MOTHS 

Moths are more diverse than butterflies and not very much is known of their food plants and habits. They are mostly nocturnal and their antennae are different to those of butterflies which have swollen ends to theirs. 

One of the most spectacular is the enormous Hercules Moth, one of the two largest in the world with a wingspan of up to 225 mm (almost 9 inches). 

Others include the Giant Wood Moth, the Four O'clock Moth – which is often seen in the late afternoon! - Hawk Moths, Fruit-Piercing Moths and the spectacular Joseph's Coat Moth.