Friday, 27 May 2011

More Moths

There seems to be an unending parade of moths to the lights each night. For one interested in studies of colour and from, this is surely the place to be.
Aethaloessa calidalis, family Pyralidae; Pyraustinae. This moth seems most active during the day. The bright orange colour is probably a warning to vertebrates to stay away.
Pollanisus sp., family, Zygaenidae.There are a number of species in the genus. All the adults are rather elegant small moths. The larvae probably feed on the leaves of Hibbertia sp.
Saptha libanota, family Choreutidae seems to be a diurnal species. Nothing is known of the larval habits of this species.
Lyclene pyraula, family Arctiidae, another common visitor at the lights that is seldom encountered during the day. Fresh moths are always spectacular.
Asota orbona; family Aganidae, female.
Anomis flava (Fabricius), family Noctuidae; subfamily Catocalinae, is an old name as its author Fabricius indicates. This moth in the Ethiopian and Oriental regions and in the islands of the Pacific as well as northern and Easter Australia. The larva feeds on cotton and other malvaceous plants.
Bracca rotundata Butler, family Geometridae; subfamily Ennominae, has a narrow range from Cooktown to Eungella, Queensland. It seems to be avoided by birds. Moths attracted to the light sheet remain there throughout the day, undisturbed by the variety of birds that eat the other moths.
Phazaca mutans, family Uraniidae, subfamily Epipleminae has an unusual stance that contributes to its resembling an imperfection in a leaf.
Vitessa zemire, family Pyralidae, subfamily Pyralinae, is an example of a moth with connections to India and the Pacific. It is less common than many other moths. It
Glyphodes canthusalis (Walker), family Pyralidae; subfamily Pyraustinae, has a rather narrow distribution in rainforests from Cape York to northern New South Wales.
Spodoptera picta (Guen.-Men.) is broadly distributed from Asia, India and the Pacific where it extends south from Thursday Island to central New South Wales. The larva lives on Crinum lilies, a number of which are native, and others are introduced. These lilies are widely used as garden plants and the moths spread in this manner.
Daphnis placida, family Sphingidae, subfamily Macroglossinae, is common in the Northern Territory and eastern Australia from Torres Strait to northern New South Wales. The larvae feed on the rainforest tree Alstonia constricta and Ervantamia angustisepala.
Nacoleia diemenalis (Guen.), family Pyralidae, subfamily Pyraustinae, is a leaf-roller and causes damage to a number of crops. Garden beans are a favourite. It is a widespread moth and is known from Africa, India, indonesia and Taiwan as well as Austrlia.
Nyctemera secundiana, family Arctiidae, subfamily Arctiinae. This is a widespread and common species that seems to be active day and night. It's slow-flying habit suggests that it is "advertising" to the vertebrate community that it is distaseful and should be avoided.
The same species in typical resting posture.
This is Utetheisa aegrotum, family Arctiidae, subfamily Arctiinae. It is hard to believe that it is in a different genus from Nyctemera. Note the spots on the thorax as opposed to the stripes on the thorax of the former.


During a morning patrol of the shadehouse, I discovered this small mosquito, Tripteroides sp. (kindly identified by Dr Scott Ritchie) feeding on the sap of the flower stem of a Sophorolaeliacattleya orchid.

You can see from the photo the mozzie has its beak in the flower. This is probably one way that viruses can be spread from pant to plant. The Mosquito family, Culicidae, has many members that feed on plant sap. They are often quite colourful.

This handsome weevil, Enteles vicinus Faust, is the first of its kind seen around here. It reminds one of "New Guinea weevils" many of which are large and colourful. Relatives of this species are associated with bananas.

Tuesday, 24 May 2011

What's This?

That's odd!
From the other side. This seems even odder!

What you see is the contortion made by an adult male Tree Cricket, Xabea atalaia Otte & Alexander, all in the interest of sex. If you look carefully at the bottom photo you'll see the cricket's wings coming out at about an 80 degree angle.

The male tree cricket either makes a hole or finds a hole in a leaf. He then inserts his head through the hole and then commences his calling song. The body is bent so that the vibrating forewings are framed in the hole. The curvature of the leaf acts as a band shell. This provides the song of the cricket with a loud and resonant quality since the leaf is acting as an amplifier. The cricket always inserts his head in the hole so that the curved portion of the leaf is where the wings are.
The adult male photographed above.
When viewed closely, Xabea tree crickets often have beautiful patterns on the head and thorax.
The leaf with the hole used by the cricket above. The shrub the cricket was using had much damage from caterpillars and I suspect the cricket found the hole and used it. Other crickets were found on the shrub.

This is not the only Tree Cricket that enhances its calling song using leaves in this way. Other species of Xabea do the same thing and the North American Tree Cricket Neoxabea bipunctata (DeGeer) uses leaves in a similar manner.

Tuesday, 17 May 2011

Aquatic Insects On The Move

The recent spate of dry weather is reducing the marshy hinterlands to the usual dry grasslands. As a result aquatic insects whose numbers have grown considerably over the recent wet season, are taking to flight, probably to find more suitable habitats.

Most of the flights take place at night. Many of these nocturnal wanderers are deflected from their flights by electric lights. This has resulted in some unusual visitors.

Recently Pygmy Grasshoppers have descended on the region in their millions. They frequented the lights around service stations in the Cairns district as well as along the storefronts on the main street of Atherton. All of the specimens I found were of the widespread Australian species Paratettix nigrescens Sjostedt.

The Pygmy Grasshopper, Paratettix nigrescens Sjostedt; family Tetrigidae.

Pygmy Grasshoppers are, as you would guess, small. This fellow measures about 8 mm in length. These insects feed on algae and diatoms along the margins of streams and lakes. They also invade on marshy ground-so long as it stays marshy where their numbers can swell. In Australia, they can often be found on perennially wet lawns. [Note the pad-like forewing called the tegmen.]
Most pygmy grasshoppers occur in a number of colour morphs. This affords camouflage on gravelly substrates where they are virtually invisible until they fly.

Along with the grasshoppers there has been an unusually large number of water beetles showing up at the lights.
Gyrinid beetles rarely appear at my lights even though a stream is only about 20m distant. But around 10 May many could be seen. These are the beetles you see on the surface of lakes or in quiet areas of streams where they feed on particulate matter that drops onto the water. They, in effect, have four eyes. Each eye is horizontally divided into two. Half is above water, the other half below. So the beetle can scan both worlds. When threatened, the beetles dive underwater and hang onto a branch or rock until the danger passes, then they release and float to the surface.
Many other water beetles, primarily in the families Hydrophilidae and Dytiscidae, fly at night.
This is the colourful dytiscid water beetle, Hydaticus vittatus, a common water beetle over much of eastern Australia.
This is a Pygmy or Dwarf Cricket, Pteronemobius regulus (Saussure). This genus is cosmopolitan with species occurring around aquatic habitats throughout the world. They don't often enter the water but live on mucky ground around the margins of streams and marshes. Several species often live sympatrically at a given locality. Males sing with distinctive soft continuous or pulsating calls, heard mostly at night.

Saturday, 7 May 2011

The Perching Dung Beetles of Wongabel

On a recent nocturnal photographic trip to Wongabel Arboretum, not far from Atherton, north Queensland, we noted number of perching dung beetles on foliage after dark. This is not an uncommon observation in tropical Australia but I was surprised to discover from colleague, Tom Weir, that three friends had written about this phenomenon some years ago.

Howden et al. (1991) reported that they found some 22 species of Scarabaeinae dung beetles at Wongabel.
A perching dung beetle, Onthophagus dicranocerus Matthews on Lantana at night. Body length approx. 11mm.

It seems that in the New World Tropics, dung beetles sort themselves on their perches by size. That is, the smaller species are found closer to the ground than the larger ones.

So the Howdens and Ross Storey recorded the height on each perch for 561 individual dung beetles at Wongabel. [Something for you to do on a dull night, but we did not observe anyone else in the rainforest measuring dung beetles or doing anything else for that matter!]

They discovered that there is no clear evidence at Wongabel that the smaller species positoned themselves closer to the ground than the larger ones.

A female O. dicranocerus atop a leaf and waiting to pick up a signal that dung is near through sensory receptors on her antennae.

Why do these beetles perch? It is most likely for the detection of fresh dung, be it from Wallabies, possums or other mammals or, perhaps, birds. But oddly enough, perching seems confined only to the dung beetles in tropical rainforests. Elsewhere in Australia they do not perch at night.

A male O. dicranocerus partially disturbed by me and the falling rain. His antennae are partially withdrawn. Note the paired projections off the head that gives the species its name.

The typical perching behaviour for rainforest dung beetles is with the lamellate antennae extended and flared.

The lamellate antenna of one of the dung beetles poised to pick up scents of a potential feast or sex!

Some general observations by the Howdens and Storey
1. The beetles preferred smooth, shiny leaves and seemed to avoid aroids and hairy or spiny leaves. [Having an experience with the nettles of Wongabel, I can agree with the dung beetles!] 2. Perching occurs on rainy or clear nights.
3. There is no stratification for height of perching based on the size of the beetle.
4. The five common perching species perched, on average, below the 60 cm level and all averaged under 10 mm in length.
5. Some generic differences were noted.
6. Australian native species shared no lineages with other continents.
7. In time the Wongabel perchers have had to shift their food preference from dung of other mammals to marsupials.
8. The perching habit of Australian beetles may have evolved independently from those of the New World.
9. Perching in some species seems to be a foraging strategy.

A note: It shows what can be accomplished with a little thought and a specialization in a group of insects. With the current trend towards the diminution of taxonomists, this sort of thought process will be lost.

Thanks to Tom Weir for comments.

Howden, H. F., Howden, A., Storey, R. 1991. Nocturnal perching of scarabaeine dung beetles (Coleoptera, Scarabaeidae) in an Australian tropical rainforest. Biotropica, 23(1): 51-57.