Monday, 6 April 2015

Delicate derbids

Almost every trip into the bush reveals a derbid or two. Pandanus palms seem to harbour several species depending on locality and possible the specific plant host.

Recent wanderings in the Emerald Falls Road, near Mareeba, Queensland uncovered a rather colourful species that has a historic taxonomic history.


The area had undergone the normal annual burning regime (for reasons known only to the local council!) and most of the small shrubs have been replaced by introduced grasses and weeds. A small amount of leaf litter has remained in pockets and this has saved some of the fauna. 

The pandanus host of the derbids was burnt but not very thoroughly. As a result these insects have survived but other pandanus insects such as earwigs, cockroaches and katydids were not to be seen.

Murray Fletcher has identified the derbids as Lydda elongata (Fabricius)

He sends the following note:
"Known host: Pandanus (Pandanaceae) (Kirkaldy 1906)
The original material of this species was collected on the voyage of the Endeavour along the eastern coastline of Australia in 1770. In the original description of the species the locality was simply given as "New Holland" and this (or variations) remained the only record listed by a number of authors between 1781 and 1832 (see Metcalf 1945). The first record of the species from New South Wales was by Schaum (1850) and Walker (1851) but, at that time, "New South Wales" could have meant any part of the east coast of mainland Australia. It wasn't until Kirkaldy (1906) that a more specific locality was provided and this was Cairns in N. Qld. It is quite possible that this species has never been found in NSW as it is defined today, with the original material coming from the Endeavour River near Cooktown in N, Qld. [update: 20.i.2011]"

Further information can be found at:
NSW Agricultural Scientific Collections Unit website at http://www1.dpi.nsw.gov.au/keys/leafhop/index.html

Fletcher, M.J. (2009 and updates). Identification keys and checklists for the leafhoppers, planthoppers and their relatives occurring in Australia and neighbouring areas (Hemiptera: Auchenorrhyncha).http://www1.dpi.nsw.gov.au/keys/leafhop/index.html


This pair was apparently courting. Note the wings of other individuals on the other side of the pandanus leaf.

Thanks to Murray Fletcher for the facts concerning this little insect.

Sunday, 5 April 2015

Cassowary Update

As Yvonne notes in her "News From Coquette Point", it is very dry here in the Wet Tropics.


The Cassowaries don't seem to mind. In the past few days the pair have been together and there has not been any aggression on the part of the female. They are probably in courting mode.
Both are resplendent in breeding plumage.




The nicks and scratches on the casque are the result of moving through the tangle of vines and dead branches that accompany their habitat.

Following the Easter visit, both seemed intent in moving up the hill to Butler Dr. Fortunately, it is not very busy today but it will be a startling encounter for anyone taking an early morning walk. The operative in this case is be calm and retreat slowly. Cassowaries are inquisitive and if you run, they will probably run with you!

Saturday, 14 February 2015

A Perfect Specimen

The Hercules Moth, Coscinocera hercules, could be the largest moth in the world. It depends on how you make the measurements. Not to worry; it is indeed the largest moth in Australia.

For the past few days since the drought broke and we have been having heavy rain and wind, Hercules have been showing up at the light. It is not unusual to find males clinging to adjacent vegetation throughout the year but to find a female, and one in perfect condition, is a bit unusual. Females are larger than the males, have more robust bodies and have shorter antennae. In addition they have shorter "tails" on the hind wings.

Adding to the interest two females showed up on consecutive nights.

Hercules moth caterpillars feed on a number of trees in our area. The Bleeding Heart, Omalanthus nutans, is a common host and we have several on the property. Readers can increase the chances of Hercules moths breeding in their area by planting Bleeding Heart tree.

This specimen measured 21.6 cm across the top of the forewings.

Friday, 13 February 2015

Who Said Cockroaches Are Not Colourful!

On a recent trip with some James Cook University students, a few remarked that they had no idea tht cockroaches could be so colourful.

Well here are a few examples that will hopefully challenge your perception of these insects as being rather dull creatures that often invade human habitation. The fact is that most species have little to do with humanity and could not survive long in our homes, restaurants, hotels etc. We just don't
"offer" what they are looking for!

This one, the Inland Ellipsidion, Ellipsidion amplum Hebard literally flew into me while I was walking on a Cairns street in the centre of town. It is a diurnal species that lives on flowers where it feeds on pollen and nectar. The bright orange colour pattern suggests Mullerian Mimicry.


The Inland Ellipsidion Ellipsidion amplum Hebard, dorsal and ventral views.

Ellipsidon cockroaches are fairly common across the continent where they have a rather similar appearance. This is among the largest of species measuring 17 mm.

The above-noted specimen was a bit battered after being carried around in a shopping bag for a few hours. Here is an example of the species in much better condition. Note the orange-tipped antennae. Other species have the antennae with white tips. In addition, the antennae are very hairy (click on the photo to enlarge), a condition quite unusual in most Australian cockroaches.

Ellipsidion is a member of the large family Ectobiidae (formerly Blattellidae) and is in the subfamily Pseudophyllodromiinae. This is quite a mouthful. However, species in this subfamily are usually very attractive. Here are a few examples.

 The Australian Allacta, Allacta australiensis Roth. 
This species lives in rainforests where it can be found only on tree trunks. It seems to prefer certain trees and not others. It measures 11 mm and is active at night.

 The Variable False Pseudobalta, Pseudobalta cinctella (Hebard)
Pseudobaltas are tropical cockroaches that are active at night. They have been found under bark during the day. The species has a broad distribution across the continent and the markings on the thorax (pronotum) are variable. It is small, measuring about 6 mm in length.
 The genus Balta includes some 39 described species in Australia. There are many undescribed species, like the one above. Baltas are distinguished on the basis of colour and morphological structures. They are nocturnal and live in leaf litter during the day. Their numbers are often great and they probably serve as food for many other organisms. All known species are active after dark.
 The Pretty Balta, Balta verticalis Hebard.
This Balta is aptly named. The specific name refers to the stripes between the eyes. It is a fairly common tropical species in northeast Australia where it can be found in rainforests and along rainforest margins. It measures about 12 mm in length.
 The Grey Balta, Balta scripta (Shelford)

One of the commonest Baltas in the northern Tropics, this species spends the day in leaf litter and is active at night. It frequently comes to lights. The pattern on the pronotum and greyish colour is very characteristic. 
The Small Mediastinia, Mediastinia australica (Shelford)

Mediastinias are more common than previously thought. They are very small, measuring less than 5mm in total body length. They are very colourful and have a very flattened appearance. This facilitates diurnal life in leaf axils and unfurling leaves. After dark they emerge to feed on particulate matter found on leaf surfaces.

The variable Speedy Cockroach, Choristima bimaculata Roth

This cockroach is another nocturnal species but it  belongs to another ectobiid subfamily, the Ectobiinae. Seldom seen during the day, adults can be attracted to light late in the evening. This species has a number of different morphs based on the pattern of the pronotum and wings. They are small, measuring less than 5 mm in total length.


Sloane's Northern Wingless Cockroach, Cosmozosteria sloanei Shaw.

This is an example of the most characteristic group of Australian Cockroaches, the subfamily Polyzosteriinae of the Blattidae. Everyone who has wandered around in the outback or the mixed woodlands of the tropics has come across these large cockroaches abroad during the day. They are very conspicuous in their colour patterns and they seem to be walking bags of nasty chemicals. They are avoided by birds and lizards. This one is about the size of a 20 cent Australian coin.

But these insects are the topic of a future blog.


Addenda: Parental Care Displayed in a Katydid

My friend Martyn Robinson at the Australian Museum in Sydney noted that in the previous blog I should have recalled an observation that he made a couple of years ago on the Superb Katydid, Alectoria superba Brunner.

This is a relatively widespread katydid of arid and semi-arid portions of the Australian continent.
The Superb Katydid, Alectoria superba Brunner, male. 

This katydid is in the Phaneropterinae, the same subfamily as Polichne, the subject aforementioned blog but it is unrelated. It is characterised by the peculiar roof-like development of the pronotum.

Martyn discovered that the species lays its eggs singly on branches and covered them with chewed bits of bark.
A small branch with a covered egg of A. superba. The ends of the eggs are delimited by the lines. The little patch of missing bark may have been used by the katydid to cover the egg. The crescentic marks are leaf scales.

Thanks to Martyn for pointing this out. It is even more embarassing that the twig sits on my desk just a few inches from my microscope and I see it every day!

Ah, the exigencies of age!

Thursday, 5 February 2015

Parental Care Displayed in A Katydid

Katydids have figured prominently in research concerning male/female relationships, sexual selection, communication, and other areas of insect behaviour.

Parental care has been demonstrated in a few species. Here I report on the concealment of eggs by a female katydid. The observation was made at Talaroo Station, west of Mt Surprise, Queensland.

Of course, the mere act of laying eggs (oviposition) in katydids is an example of parental care to some degree. Katydids lay eggs in the ground, in leaf tissue, in wood and other media. But coating the egg with an external substance is unusual.

In the Guide to the Katydids of Australia (Rentz, 2010: 170) I noted a female Polichne argentata that had just completed laying an egg on a twig and then covering it with a bit of dirt that it had gathered from the ground beneath.
Polichne argentata with egg just laid and covered with bits of soil

Recently I made a similar observation on another, probably undescribed, species of Polichne. I was fortunate to have my camera at the ready and was able to record most of the event.

In this observation, the katydid first chewed a piece of bark from a eucalypt.



Then it guides its egg into the selected crack in the bark of the tree.

 The act of oviposition.
 The egg deposited.
The final act of plastering the egg with the chewed bark it had gathered just prior to oviposition.

So what is the "reason" for the unusual ovipositional strategy? Covering the egg with a foreign substance may aid in reducing desiccation in the normally dry habitat of the Australian outback. It may also afford some protection from minute hymenopterous egg parasites.  Or it may be none of these explanations. It seems less likely that it obscures the egg from potential vertebrate predators. 


Literature Cited

Rentz, DCF 2010. A Guide to the Katydids of Australia. CSIRO Publications, Pp. 1-214. CSIRO Publishing, Collingwood, Vic.


Wednesday, 31 December 2014

Stylops!!


Remember to click on the photos to enlarge


Members of the insect order Strepsiptera are frequently collected by entomologists but few recognise them for what they are. These insects are internal parasites of a variety of insect orders. Most have complex life histories. First instar nymphs are free-living and look nothing like either parent. Females are obligate internal parasites of their hosts in all but one family whilst males are free-living for a very brief period during which they find the female, mate and then die.

Females often appear as a dark spot on the abdomen of the host. This can easily be overlooked as a wound or other imperfection by casual collectors.

Strepsiptera are believed to be most closely related to the beetles. The fore wings of male strepsipterans are reduced and the hind wings are expanded for flying. This is similar in some respects to beetles of the family Rhipiphoridae. 

Members of the order Strepsiptera are often called "stylops". This is a bit of a misnomer because the Stylopidae is only one of several families in the order. Insects that are parasitised by strepsipterans are said to be "stylopised" to add further confusion. 

Some 30 species of Strepsiptera have been described from Australia. They are parasites of a fairly broad range of insects. Silverfish, orthopteroid insects, bugs, flies, bees and wasps are known hosts. They have been studied extensively by J. Kathirithamby and her colleagues.

Recently my friend Graeme Cocks discovered a male "stylops" in one of his Malaise traps. His photos are of such excellence that they prompted this blog.
G Cocks photo




G Cocks photo

This appears to be a species in the family Corioxenidae, subfamily Corioxeninae. These insects are parasites of bugs (Heteroptera). 

The forewings are the dark twisted structures just behind the eyes. Both the eyes and the thickened grey antennae are peculiar and are probably involved with host-finding. Males have only a few hours to find their mates in some species.

A few days later while collecting and photographing insects on Mt Baldy, near Atherton, Queensland I found a female Cone-headed Katydid, Pseudorhynchus sp.,  with the tell tale dark mark of a stylops on its abdomen.

Pseudorhynchus sp., female

dark spot of a stylopised insect

Dissection of the abdomen of the katydid revealed that its eggs were intact seemingly unaffected by the parasite. The sac-like abdomen of the parasite was tightly affixed to the hosts abdominal wall where it did not seem to interfere with any bodily function of the host. If so, this is quite different from some of the examples of other hosts. Behaviour, structure and sexuality can be severely changed in certain bugs, for example. The only "odd" aspect of the katydid was that it is slightly smaller than I would have expected from a female of its species. 

From what I can tell, this is a very different species from the male Graeme photographed. It seems to be a member of the family Halictophagidae.

What you see is the opening called the brood passage, the mandible, maxilla and probably the antenna of the female. Males fertilise females through the brood passage. 

Katydid's abdomen opened to expose the entire female "stylops". 

The Strepsiptera are an unusual group of highly modified insects. Their morphology and biology  have been relatively well-studied compared to many other insect groups.

I am grateful to Graeme Cocks for allowing me to use his excellent photos of the male he found in his trap.