A Cold Night On Mt Baldy

It was a cold late winter's night with the wind blowing, trees creaking and mist blanketing the tree tops. We thought we were in for a poor night.

It seemed that not much was on offer.

A few dung beetles were at the ready:

But they had to be optimistic as we saw only a bandicoot. However, wild pigs had dug up the gutters of the dirt track looking for whatever they could find.

A few frogs were about

I suspect if was slim pickings for the frog population, especially those waiting on leaf surfaces.

Three cockroach species provided the interest for me. All are in the large and varied Australian endemic genus Johnrehnia. [The peculiar generic name is easily explained. It was named in honour of John W. H. Rehn, son of the famous Philadelphia entomologist, James A. G. Rehn. John studied cockroaches, especially their wing venation and how it relates to their classification.]

Two of the three species illustrated below were already known from Mt Baldy. The third was seen for the first time.

 Johnrehnia lakebarrina Roth was described from Lake Barrine, of course. The lake is not far from Mt Baldy. This attractive cockroach lives in leaf litter during the day but emerges after dark to feed on the bits and pieces of particulate matter that accumulates on leaf surfaces.

 Johnrehnia tibrogargana Roth was named for Mt Tibrogargan, one of the peaks in the Glasshouse Mountains of southern Queensland. It was a poor choice of names because even at the time it was described, it ws known from a number of localities along the coast and inland north to Cooktown. J. tibrogargana is common on leaves after dark but on this evening it seemed too cold for it to do much more than wander about in the leaf litter on the ground. On warmer evenings this cockroach is fast-moving and readily flies at the slightest disturbance.

Johnrehnia ruggi Roth was the find of the evening. This species was named in honour of Dr Doug Rugg, former student of Dr H. Rose, University of Sydney. This species appears to be restricted to leaf litter and does not ascend to feed on leaves after dark. That is probably why we had not seen it in the past. All that we saw wereon the ground and several were in cracks and did not appear to be interested moving much farther abroad.

 Johnrehnia species were placed in three species groups by Roth based on the shape of the male's subgenital plate. This is a distinctive structure used in cockroach taxonomy. Both J. tibrogargana and J. ruggi were placed in the Tibrogargana Group.

The subgenital plate consists of all sorts of gadgets having to do with copulation. Below we see the plate itself plus some of the internal structures comprising rods, hooks and the like. One of the neat things about cockroaches is that in many species their genitalia are not bilaterally symmetrical. This means that the left side is different from the right. So if a successful mating is to take place, the bits of the male must fit into specific counterparts in the female. If not, then a successful mating may not be achieved.

 J. tibrogargana, male subgenital plate, dorsal view. (Modified from Roth, 2000)

J. ruggi, male subgenital plate, dorsal view. (Modified from Roth, 2000)

Taxonomists use the shapes of the bits and pieces of the male subgenital plate to help identify species. There are many other features of a cockroach that are distinctive as well. But it is easy to see the differences in the two species above.

Tibrogargana Group species, and there are five of them, have the hind margin of the plate complex with the corners with setal and spine-like structures. In addition, the subgenital plate is not flat but subcylindrical. Here is is illustrated and flattened out.

J. lakebarrina male subgenital plate, dorsal view. (Modified from Roth, 2000)

It is easy to see the differences in the subgenital plate of this species when compared to the two above. It is a member of the Hodgkini Group along with more than twenty other species. This group is distinctive in that its species have the hind margin of the plate simple with the right and left styles (the appendages in the middle) dissimilar, the left one being small and cylindrical. In addition, the plate lies flat and is not subcylindrical.

So there is more to a cockroach than most people realise. They are complex and interesting organisms that have been around long before the dinosaurs. Australia has a remarkably large fauna of these insects. Only a half dozen species cause problems. All of the others (over 500 in Australia!) are at home in their habitats which do not include human dwellings. They are extremely common, especially in forests. They must be very important in the decomposition of leaf litter and the ultimate health of most habitats. Many are very colourful and attractive. You will be seeing more of these in the future!

Literature

Roth, LM. 2000. The Australian cockroach genus Johnrehnia Princis (Blattellidae; Blattellinae) Oriental Insects, 34: 83-192.

Bombs Away!

For a few days recently it was unsafe to walk under our large Flindersia tree. [There are 14 species in the genus and this one is probably F. bourjotiana]. The pods were being dropped from about 20-30 m height!

Each pod measures about 9.5-10.5 cm in length and covered with stout spines. So being hit by one from such a height would not be a pleasant experience.

 Most of the pods were chewed and partially opened.

 A normal Flindersia pod has 5 star-like arms and a seed in each.

The culprits were masses of Sulphur-crested Cockatoos. With an abundance of riches, the birds would feed partially on a pod and then move to the next one. Multiple pods are borne on stems so many are dropped without a beak mark.

Once on the ground, the pods dry out quickly and open within a day or two. That allows birds and ground dwelling mammals to partake of the riches since most of the seeds are still intact within the pods.

At first one might be upset with the seemingly wanton destruction brought on by the feeding birds. But it does have a beneficial effect of providing food to other animals. Some, like the Musky Rat-Kangaroo,  move the seeds away and store them for later use. This disperses the seeds and probably gives rise to new trees well away from the mother-tree.

After about 3 days of concentrated work by hoards of cockatoos, they left and the ground is now littered with the pods that are providing food to other creatures of the forest.

A Mystery Solved

In a previous blog I noted a couple of caterpillars that I would attempt to rear to maturity. Until now the efforts went unrewarded.

We know the identity of one of them.

 To review, I noticed the white caterpillar on tree trunks covered with lichens and algae.

The individuals had an irregular appearance. Dissection of one of them revealed that each was covered with the lichen material that was held in place by threads of silk.

 The caterpillars move with an arching gait and travel up and down the trunk over 2m per day. But they always seem to return to nearly the same place each day.

The caterpillars seem to feed on the white-patch lichens but because of the concealment of the mouthparts, it is difficult to determine if they are feeding on anything else. It's obvious that the caterpillars incorporate some of the green material into their camouflage. Ants and other insects travel past the caterpillars and pay them no attention. 

This year, the caterpillars were found on palm trunks and the trees where they were last year had no caterpillars on them at all.

I took two of the larger larvae and scraped a few bits of lichen off one of the trunks and placed it in a container. After a few days a cocoon was formed.

 The coccoon. Each cocoon was borne on an elongate stem. After 29 days, at room temperature, the moth emerged.

Enispa prolectus (Turner): Noctuidae; Acontiinae

The moth is relatively common and turns up regularly at the light sheet. Seven species of Enispa are known from Australia. It seems that little is known of their habits. Common (1990) records one species, E. plutonis (Lucas), living in spider's webs where they feed on the detritus such as dead leaves and the left-overs from the spider's catch. The caterpillar is naked and not covered with any detritus.  Its pupa is suspended without any cocoon by its anal hooks. This is very different from E. prolectus. With E. prolectus, there is a cocoon that is suspended on a stem which is firmly attached to the substrate by silk.

The next step is to find the distinctive cocoons in the habitat. They most likely move to adjacent vegetation or, perhaps, under loose bark. This is in short supply on rainforest trees.

Thanks to Buck Richardson, and his moth identification site, for aid in identifying the moth.

Literature

Common, IFB. 1990. Moths of Australia. Melbourne University Press. Pp. 1-535.

Orchid Foes--and Friends (a follow-up)

A daily survey of the orchid collection provided this little vignette.

The Orchid Weevil, Orchidophilus aterrimus (Waterhouse) was about to be attacked by a Jumping Spider.

Ah, I thought what a great thing. Biological control in action. But alas, it was not to be.

But after a fraction of a second, the spider released the prey and moved away. Several bouts were observed in just a few minutes time and then the spider hopped away. Note the weevil is firmly attached to the substrate. So that got me to thinking what makes a "successful" pest.

In this instance, perhaps, the spider could not penetrate the tough exoskeleton of the weevil. Entomologists will tell you difficult it is to pin a large weevil. A #5 stainless steel pin often will not penetrate the exoskeleton of the specimen. If this is working in this example, it is surprising the spider's chelicerae could not find a membrane or other soft point to penetrate. But after several attempts it could not.

And, perhaps, the weevil excreted a chemical of some sort that discouraged the spider. But if this were the case, the spider would not have made repeated attempts at capture.

The weevil stayed "glued" in the same position for 15 minutes until I decided it was time for the alcohol treatment. The spider wandered off. There are not many food sources in the shadehouse so I hope the spider will sharpen its chelicerae for the next encounter.

The spider. It is a Jumping Spider, family Salticidae. There is a great spider site on the web dealing with Aussie spiders. But I cannot reliably identify the genus of this little spider so will not guess. Perhaps, a reader will be able to put a name on it.

Things lepidopterological

Recent night trips on cold (16C!) winter's nights have provided observations to compensate from the distinctly non-tropical temperatures.

 Roadsides in the  mixed woodlands not far from the rainforest have been clothed in a blanket of bright yellow with the flowering wattles (Acacia spp.). Close examination of the flowers revealed a yellow caterpillar consuming the blossoms.

 The arching gait suggested a looper, a member of the Geometridae.

Traminda rubra Holloway: Geometridae; Sterrhinae                
B Richardson photo

A few were removed with some blossom and after a few days they formed a chrysalis and about 10 days later the moth emerged. This moth has two colour morphs. The brown one shown above and a green morph. It is not uncommon and is often found at lights in the rainforest where there are also acacias but of different species. [Thanks to Ted Edwards for noting the name change for this moth.]

 This little moth, a member of the huge family Oecophoridae, was common sitting on grass blades after dark on a very cold evening in the Davies Creek area, Qld. Grass of several species was deep and green.

 One might think the moth is therefore associated with grasses. Well it might be but a female was observed ovipositing (egg-laying) in the bark of a Baker's Oak,  Allocasuarina torulosa.

Ovipositing female.

Perhaps, the eggs hatch and the tiny larvae drop to the ground and live on grass roots until they emerge and then sit on the grass blades after dark. Laying ones eggs in bark at the base of a tree like Baker's Oak is a rather precarious activity late in the winter at this locality. Soon the "fireies" will be setting the habitat ablaze with their "prescribed" burning. From the looks of the trees in the area, this a regular process. It would be very lucky for the eggs of this moth to survive what appears to be ahead for this habitat. But then, obviously some do survive such treatment.

Orchid Foes Revisited

The site of these feet on the developing flower stalk of a treasured orchid is a cause for some concern.

This is one of the orchid weevils, Orchidophilus aterrimus (Waterhouse). I have written about this before. Several adults of both sexes have been found on developing stalk. Where the larvae reside is not known but I suspect they occur in the pseudobulbs of the plants themselves.

A few days after feeding this spot appeared on the stem apparently where the weevil had inserted its beak to feed. I'll watch this and see if it results in any damage to the flowers.

A few days later, this critter was found feeding on the developing flower stem of Dendrobium speciosum.  Closer examination revealed what it is.

 The lines on the thorax are the giveaway.

It is a nymph of a species of Siphanta. I have written about these before as well. I have no data on what this single nymph might have done to the developing flowers, but it was not given the chance to proceed with its development! Spring is springing.

An Unexpected Discovery

Three times in 12 years Emerald Forest Doves have mistaken our windows as extensions of their forest habitat and have paid the price. Yesterday one bird met its fate. When I picked it up I noticed a very large (relative to the size of the bird) Louse Fly. I have written about these flies before when they showed up at the light sheet. Louse Flies are external parasites of birds and mammals in the family Hippoboscidae. You can get an idea of the diversity of the family from the images on the site.

Louse flies are remarkably adapted for existence in bird feathers. Some species detach their wings when they have found the proper host. Eggs mature within the mothers and the living larvae are deposited away from the host and they have to undergo the lottery that many parasites are forced to endure. The right host has to come along at the right time for the larvae to continue their development.

The flattened appearance of the adult likens them to lice, hence the common name. Several are parasites of livestock and are transported around the world on their hosts. Australia has several introduced species that are just such pests.

The fly measured approximately 11mm in length.

The business end. The piercing mouthparts enable the fly to suck blood from the host, probably from the feathers. The flies are very fast-moving. This enables the fly to dodge the preening activities of the bird without being harmed by its beak.

But nothing is straight-forward in this world. The odd creature below was also found within the feathers of the poor bird.

It is may not associated with this fly. It does not seem to be a puparium. So what is it? Maybe a reader will shed some light on the subject.

Frontal view. It does not seem to be a larva. It did not move and there seems to be no opening in the midst of the teeth-like structures. Any ideas?

Along related lines, have a look at Piotr's blog on another, much more robust, parasitic fly.