Saturday, 18 June 2016

The Peppermint Stick-Insect

Remember, click on the images to enlarge

Undoubtedly the insect icon of the Daintree Rainforest on Cape York Peninsula, north of Cairns, Queensland is the large, flightless Peppermint Stick-Insect, Megacrania batesii (Kirby). I have written about this beautiful insect before and you can find details about its occurrence and history at this reference. It is such a nice insect that it deserves an additional blog.
 At Cape Tribulation it can be found within centimetres of hikers that move up and down the trail. No mention of it is to be found on the descriptive sign but tour operators know it is there and often point it out to their customers.
 The Peppermint Stick Insect, adult female Megacrania batesii; Phasmatidae; Platycraninae

It is a large insect with females measuring over 110 mm in length. They are beautifully coloured with blue, green and yellowish green predominating. The sticks reside within the midrib of their host-plant, Pandanus tectarius. They often "sun" during the day in a characteristic posture. They have excellent eyesight. When danger threatens, they scuttle back and forth in the midrib, often backing down to the base of the plant where the serrations along the margins of the plant offer considerable protection.
The common name of the stick is based on the behaviour of the insect when it is greatly disturbed. Prothoracic glands (arrow) exude a volatile liquid that smells to us like pleasant  peppermint. This is so volatile that it can be detected several metres from the source. It is amusing to watch the reaction of hikers when they first detect the odour as the move by. Most think the smell is a plant of some sort but are surprised when they are advised of the source.
 The small nymphal stages of the Peppermint Stick are also strikingly coloured.
 Most of the Pandanus plants are not occupied by the sticks and display no damage.
 With a little practice, one can sight plants that are likely to harbour the sticks. Note the condition of the leaves in the background. This is from feeding but it can be many weeks old.
 These leaves have been eaten by several sticks over time. This feeding damage is severe and obvious. At a picnic area to the south, the sticks almost totally defoliated the host plants.
Some patches of Pandanus are more affected than others. Why is this so? No one has the answer. It could be that some plants taste different and therefore, there are plants the insects prefer. Or it can just be serendipity-they have patchy distributions because they have patchy distributions. There is the opportunity for some research here.

The Peppermint Stick-Insect has an odd geographical distribution. It is known from the Solomons, New Guinea and the Bismarck Archipelago. In Australia it has been found from Cape Tribulation south to Clump Point, south of Innisfail.

The egg-laying habits of the females may have the answer to its spotty distribution. Eggs accumulate in the detritus at the base of the leaves in the axils. During cyclones, clumps of Pandanus often become dislodged and float out to sea. Some may reach shore at a locality far removed from the source. Perhaps, this is how the Peppermint Stick-Insect gets around. But it does not explain why some plants are occupied and others are not.

Tuesday, 31 May 2016

Croc Attack-A Lesson in Carelessness

It seems appropriate to revisit a recent blog: A Beautiful Day in the Tropics

Thornton Beach, north Queensland
This is approximately the same spot where the woman was taken by a crocodile yesterday evening. The entire area is well signposted and it is a notorious place for crocs. With Cooper Creek adjacent to Thornton Beach, it is ideal crocodile habitat with sandy beaches and fringing mangroves. In fact there is a small tourist business there with a boatman who takes people on tours of the mangroves to see the crocs in their natural habitat. In a few minutes time he has them observing crocodiles in nature.

It is very bad judgement to enter the water during the daytime and unthinkable that one would do so after dark. After dark is the time the crocs do their serious hunting. These women were sitting ducks for a large crocodile. As you can see from the photo below, they are known to the frequent the area. It is even very poor judgement to walk along the shoreline after dark as the crocs often venture onto the beach and wander into the strand flora. In doing so, a beach walker would place him or herself between the croc and the water- a deadly combination.

And being the election season in Australia, politicians have entered the discussion with one bringing in the old chestnut of time to consider a "croc cull". What is the advantage of that? Most tourists who come to north Queensland want to see two icons: the Great Barrier Reef (dying due to the effects of climate change and poisoning by agriculture) and crocodiles. Topline predators are always sought after by tourists. It is true in Africa with lions, India with tigers and Alaska with Polar bears.

And what would a croc cull solve? Would anyone feel safe venturing into those waters after same? There just might be one left that avoided the hunters guns. Who would want to be the first to enter the water?

It's best for people to use their heads and heed the signs. It's the crocs place. Let them be and treat all activities in that region with CAUTION.


Saturday, 14 May 2016

All Those Little White Moths

On the evening of the 12th May 2016 there was a mass emergence of little white moths called Chamaita barnardi (Walker). They were so numerous they appeared as snowflakes. The tiny moths seemed to be everywhere in the Kuranda area even on the busy Kennedy Highway leading to Cairns. As far as I can tell, the larvae are unknown. The following night, there were not so many.
 Chamaita barnardi (Walker)
These moths measure only 5-6 mm so there must have been millions of them emerging at approximately the same time. What triggered such an emergence and where where the larvae?

This little moth seems to be seasonal. It is not always found at lights as are the two below.

All belong to the Tiger Moth Family, the Arctiidae, and are placed in the subfamily Lithosiinae. I have dealt with these moths before in this blog.

Other members of the Lithosiinae were found at the lights with the little moths:
 Lyclene quadrilineata (Pagan.)
Teulisna bipunctata (Walker)


Tuesday, 3 May 2016

Meet the New Mrs--Cassowary, That Is

well here she is. She seems much larger than the other two female cassowaries we have had here. She has been named "Socks" because of her large, paired wattles. She seems to be a young bird. The feet are not scarred and the casque is smooth and even and without notches that accompany older birds from their trampling in the forest.

This poo sample consists mainly of palm fruits. She returns several times a day to feed as more fruits drop to the ground. Birds and mammals will feed on the exposed seeds and most will be carried off within a few days.

Saturday, 23 April 2016

He's Back-Mr Cassowary Returns

After a period of about 2 months, we had a visit from the local resident male cassowary. His chick had been run over by a vehicle on Black Mountain Road over the Easter Weekend.

There are so many trucks and other vehicles using Black Mountain Road, that we are always worried he will be hit when he crosses the road to get to Top of the Range.

Caterpillar Parade

The other day while walking up our driveway, I came across a group of Processionary Caterpillars.
From a distance, the caterpillars look like a moving snake.

 They are not attached to one another but apparently follow a pheromone trail laid down by the leader. Above shows the lead caterpillar. How the "leader" is determined is a good question. Occasionally something goes wrong and the caterpillars form a circle and the hopeless caterpillars circle about for hours until something causes them to diverge.

 The larger caterpillars are probably the females. A total of 53 caterpillars comprised this procession.

So what is happening here. The caterpillars live on acacia an other trees in large groups within clumps of webbing. When the caterpillars are mature, they leave the host tree and follow-the-leader to an area of soft, pliant soil where they bury themselves and form cocoons. After a period of time, the adult moths will emerge.
The adult, a moth Ochrogaster lunifer, family Notodontidae, subfamily Thaumetopoeinae. At this writing, the moths are not uncommon around lights after dark.

A WORD OF CAUTION
The fine hairs on the caterpillars are to be avoided. They are urticating can cause serious skin irritation and if there are accumulations of webbing, cast skins at the base of the host trees, these can provoke allergies in humans.

Dogs can come to grief by physically encountering the caterpillars. Should they step on the line or sniff the caterpillars, the hairs can become embedded in their paws or tongue when they lick the source of irritation. If the hairs remain embedded, and they often do, they can cause infection which in extreme cases can result in the tongue becoming necrotic and leading to amputation.

Caterpillar with a Problem

On 11 April 2016 while doing some night photography in the bush on Clohesy Road, nr Koah, Queensland, we discovered a caterpillar with a problem.
This caterpillar, probably a lymantriid, Euproctis, perhaps lutea, had been parasitised by a small wasp early in its life history. The white pods are cocoons of the wasp, not eggs. The eggs had been laid internally by the wasp a couple of weeks before and the larvae developed within the caterpillar feeding on substances in the body fluids of the host.
 The unhatched cocoons with caps intact.
 Three days after collection of the caterpillar, the wasps emerged leaving the empty cocoons.  The parasites are wasps of the family Braconidae, probably in the genus Apanteles. The caterpillar remained active, moving around until 22 April, 2016 when it died. It had been doomed and would never have been able to form a cocoon and become an adult moth. This is an example of natural biological control

The caps indicate the hatching of the cocoons. There were 13 female  and 4 male Apanteles wasps.
The wasps. The female is in top. Note the short ovipositor that is used to insert eggs into the host caterpillar.