Sunday, 29 June 2008

Mothing - 29th June 2008

I put the moth trap out last night. Someone who shall not be named left the waterproof choke housing in the drive way and another person who shall also remain nameless drove over it. Amazingly it still works although it certainly isn't waterproof anymore :-) Being winter I wasn't expecting too much but I managed three moths, two of which are new for my backyard. Interestingly only one was actually in the trap. It was a Tree Lucerne Moth - Uresiphita ornithopteralis like the one I posted on Friday.

Of the two new moths, one was on a nearby wall and the other was on the ground so it certainly pays to look around the area of the light trap. There was a Geometrid moth, Casbia crataea and another which I'm yet to identify. If anyone recognises it please let me know. This afternoon I also found a small Psychid larval case on a silver wattle (Acacia dealbata).

Update: The unidentified moth turned out to be Paralaea porphyrinaria (Guenee, 1857)

Casbia crataea- (female) FW length 20mm


Paralaea porphyrinaria - Forewing length 27mm


Psychid larva on SIlver Wattle



Friday, 27 June 2008

Tree Lucerne Moth - Uresiphita ornithopteralis

  • Class: Insecta
  • Order: Lepidoptera
  • Family: Crambidae
  • Species: Uresiphita ornithopteralis (Guenee, 1854)


The imago

This is a very common moth locally, with a long flight period running from November to July. The larvae feed on various plants of the family Fabaceae including English and Spanish Broome, as well as some Acacias. We have a bit of a problem with the intoduced Broom, Genista monspessulana, on our block so it is a good species to have around. I have seen young broom plants completely defoliated by this caterpillar.


Larva

Batches of 10 -15 eggs are laid on the upper leaf surface of the host plant. These hatch after about 2 weeks. The larvae go though 4 instars over a period of 4 to 8 weeks reaching 18 - 30mm in length. after which they pupate on the ground within a finely woven, loose cocoon. Pupation can last anwhere from 9 to 114 days.


Larvae on Cape Broom -Genista monspessulana

These are fairly easy to rear from larvae. I have done so using just a chinese take-away container as you might be able to detect in the photo below. Just provide fresh food and keep the container clean and aired so as to avoid fungal attack.


Cocoon - the larva within has not yet pupated

The Tree Lucerne Moth is considered by some to be a subspecies of the Uresiphita gilvata (Fabricius, 1794).


References:
  • Common Moths of the Adelaide Region - McQuillan & Forrest, 1985
  • Moths of Australia - Common I.F.B, 1990



Brown Flatworm - Notoplana australis

  • Phylum: Platyhelminthes
  • Class: Turbellaria
  • Order Polycladida
  • Family: Leptoplanidae)
  • Species: Notoplana australis



Most Turbellarians are less than 10 mm long which makes the Brown Flatworm seem rather large at up to 40mm. This species is distributed along the south-east Australian coastline including all of Tasmania and can also be found in New Zealand. Certainly here on the NW Coast it is fairly common on the underside of rocks at low tide.

It is carnivorous, feeding on bryozoans and other sessile invertebrates (attached to objects). It it sometimes seen as a problem for commercial shell fisheries as it has been found to eat oysters, hence it's other common name of Oyster Leach. However, it is believed that this flatworm only enters the shell when the oyster is already dying from some other cause.

The Brown Flatworm spawns all year with a peak in spring and early summer. The egg mass is a coiled, gelatinous string of individually encapsulated eggs. The eggs are only 120-125 ┬Ám (about 1/8th mm). The larvae hatch out after 12-14 days. It has planktonic larval stage with a gradual metamorphosis to a juvenile flatworm over a period of about 3 weeks.

References:
  • Diseases of cultured molluscs in Australia - Lester, R.J.G. 1990
  • Australian Marine Life - The Plants and Animals of Temperate Waters - Edgar J. E. 2000
  • The embyonic and laval development of the turbellarian Notoplana australis - Anderson DT 1977 - Australian Journal of Marine and Freshwater Research 28(3) 303 - 310


Thursday, 26 June 2008

Giant Tasmanian Cave Spider - Hickmania troglodytes

  • Order: Araneae
  • Family: Austrochilidae
  • Subfamily: Hickmaniinae
  • Species: Hickmania troglodytes (Higgins & Petterd, 1883)

The Giant Tasmanian Cave Spider was first recorded in the limestone caves at Mole Creek in 1883. It is endemic to Tasmania but is widely distributed throughout the state. Despite it's common name it is not confined to caves. Any cool cavity large enough to support it's extensive web may be used. They have even been found under bridges and in large hollow logs. I have seen them in several places including Gunns Plains Cave and in a mine adit near Montezuma falls which is where the following photographs were taken.



The females body length can be up to 20mm and the males 13mm. However the leg span can be up to 180mm. They build a large horizontal sheet like web on the roof of the cave or cavity. One web was recorded to be 122 cm long by 61cm wide. The large pear shaped egg-sac is about 49mm long by 26mm wide. When in caves it is left undecorated as seen in my photo below. However if the spider is, for example, in a hollow log, it will cover the egg-sac in small particles of wood and debris. Spiderlings emerge from the sacs after 8-10 months. This spider is also noted for it's long lifespan, possibly lasting several decades.


Female with egg-sac
Reference:
  • Some Common Spiders of Tasmania - Tasmanian Museum & ArtGallery
  • Tasmanian Cave Spider (Fact Sheet) - Australian Museum


Wednesday, 25 June 2008

Stick Insect - Ctenomorpha chronus

  • Order: Phasmatodea
  • Family: Phasmatidae
  • Subfamily: Phasmatinae
  • Ctenomorpha chronus (Gray, 1833)
In the two years I've been at at this site I have never seen this species but in the last 2 months (April to June) several females have been found on the walls and windows of the house.


There are only 3 species of Phasmids in Tasmania. This one, Ctenomorpha chronus, belongs to the subfamily Phasmatinae while the other two belong to the subfamily Tropidoderinae.


Details of compound eyes and palps


Details of head and prothorax

This females of species can grow to 176mm, however, they can appear longer as they rest with their forelegs outstretched. They blend in well amoong Eucalyptus stems. While males are fully winged, the short tegmina and very long cerci suggest this one is a female.

Short tegmina (wing covers)


Very long cerci



Basic Introduction to the Lepidoptera

The order Lepidoptera covers the moths and butterflies. The order is second in size only to the Coleoptera (beetles). It contains over 120 families and over 160,000 described species. Australia alone has over 20,000 species.

Moth or Butterfly
An often heard question is, "what's the difference between moths and butterflies?" Well in fact, there are no taxonomic classifications that separate the two. However, some families are usually referred to as butterflies and some as moths based on some general differences. The butterflies usually have clubbed antennae and their wings are held vertically when at rest. Moths often have feathery or other non-clubbed antennae and their wings lie flat when at rest. Of course there are always exceptions to the rule.

Examples of Lepidopteran wing scales

Imago (Adult)
An adult stage moth or butterfly is also known as an imago (pl. imagoes or imagines). They have two pair of wings although in some female moths, the wings may be reduced to vestiges (brachypterous), or may even be completely absent (apterous). The name, Lepidoptera literally means scaly wings. The wings are covered in tiny scales which give them there many and varied colours and patterns. The various families are mostly separated by the wing venation, however, many families also have other traits which are easier for the amateur to notice.

Examples of Antennae

Females emit pheromones. Males, often with enlarged antennae, are able to detect these pheromones and can locate a female over a considerable distance.

There are various tactics for overwintering. Some hibernate as adults while other survive the winter as larvae or as eggs.

The adults have their mouthparts adapted for sucking with a curled proboscis. They feed on liquids such as nectar, honeydew or in some cases by piercing fruit. However, not all adults feed. Some have greatly reduced mouthparts and do not feed at all. Instead they live out the remainder of their life using up the reserves stored in the larval stage.

Egg
The first stage in the life cycle is the egg or ovum, There are rare examples of viviparous species which in fact produce live young, for example, some Coleophora spp in Europe.

Eggs of the Helena Gum Moth

Depending on species, the eggs can take anywhere from a few days to many months before hatching with some species overwintering in the egg stage. Weather conditions such as temperature, humidity, and rainfall can also effect the time of hatching. For example some species will hatch after a fall of rain as this will ensure fresh plant growth as a food source.

Eggs are usually laid on the food plant and can be found in crevices, on leaf surfaces, on flower buds etc. Polyphagous species, those that feed on a large variety of plants, are less fussy about where they lay their eggs. The eggs can be laid individually, in clumps, in neat rows or even stacked in little piles. Most eggs are covered in a kind of adhesive to stick the eggs to the surface of the foodplant and sometimes they are also covered with scales from the moth. While some species only lay a few eggs, others are capable of laying many thousands.

Larva
The larvae are usually called caterpillars. They are soft bodied with a sclerotised head capsule. The three segments of the thorax each carry a pair of legs. The abdomen consists of 10 segments. In addition to the three pairs of thoracic legs, the caterpillar's abdomen bears prolegs, which are sometimes referred to as false legs. There are usually five pairs. They are found on abdominal segments 3 to 6 with another pair on the last segment (10th) This last pair of prolegs is called the anal prolegs or anal claspers. There is usually a gap (segments 7-9) between the abdominal prolegs and the anal prolegs although there are exceptions such as the family Micropterigidae which have 8 pairs of prolegs. This gap can be used as a rough guide to separating caterpillars from the similar looking larvae of sawflies (spitfires). However, a more accurate method is to look for the presence of a ring of hook-like spines around the prolegs. These are called crochets and they facilitate clinging on to various surfaces.

Prolegs and True Legs

There is a silk producing gland called a spinneret on the labium (lower lip). Some caterpillars when disturbed will drop from their food plant attached by a long thread of silk. Some even blow in the wind attached to such a thread as a means of dispersal. The more obvious use for their silk to produce protective shelters. For example some will tie together leaves to form daytime shelters, only coming out to feed at night. Others produce cocoons during periods of dormancy (aestivation). An unusual example comes from Hawaii where several species including Hyposmocoma molluscivora have been found which tie down small snails with their silk before eating them. This is unusual in respect to the use of the silk to trap prey as well as in their carnivorous diet. The most common use of silk is is to produce a cocoon or underground cell for the protection of the pupal stage. The pupal cocoon may incorporate other materials including the hairs from the caterpillar.

The larvae are generally herbivorous although there are some exceptions. They feed on foliage, flowers, roots, and some even bore through wood. Some microlepidoptera feed on the cells between the surfaces of leaves resulting in the familiar leaf mine patterns. Note: not all leaf miners are lepidopterans. Some hymenopteran and dipteran larvae also create leaf mines. The larvae of the Pond Moth (Hygraula nitens) are aquatic and feed on the stems of water plants.

Pupa
The pupa of a moth or butterfly is often referred to as the chrysalis. With neither legs nor wings the pupa can do little more than wriggle and so it is rather defenseless. Different species use various methods of increasing there chance of survival. The most obvious is the cocoon. While the butterfly chrysalis is generally rather exposed with perhaps just a little silk to attach itself, moths will often build a cocoon. These can vary from a few very loosely woven threads to extremely tough bags which are difficult for a human to open let alone a bird. The Gum Moths make a tough a cocoon like this. When it is time to emerge, they secrete an enzyme which softens one end of the cocoon. They then use sharp spines at the base of their forewings to cut there way out.

Silk cocoons can be made between two leaves or by tying twiggy branches together. They can also be made among the leaf litter or used as a lining in an underground cell. The larvae often incorporate other materials into the cocoon. For example plant materials for camouflage or the caterpillars hairs. In the case of urticating (stinging) hairs, these can be just as potent on the cocoon as on the caterpillar. Not all moths use a cocoon. In some cases the pupa just lies naked among the leaf litter or even on the soil surface. However, the similarity in shape between the pupa and some animal droppings may in itself be a defense.

It is during the pupal stage that the adult moth or butterfly develops. This involves all but the vital organs turning into a gooey liquid, after which the adult form develops. The entire process can take anywhere from less than a week to many months. Some species use the pupal stage for overwintering. Another strategy for the overall survival of the species is for some pupae to delay development until the following year This way, if the population takes a dive one year due to cold weather, or drought etc, then they still have a second chance the following year.

Further Reading
Well I hope you got something out of reading this basic introduction. However, If you really want to know more about the fascinating lives of the Lepidoptera then here are just a few recommendations for further reading:

  • Enjoying Moths - Roy Leverton - 2001 - Poyser Natural History Books
  • Moths of Australia - I.F.B Common - 1990 - Melbourne University Press
  • Moths of Australia - Bernard D'Abrera - 1974 - Lansdowne Press
  • Flying Colours - Common Caterpillars, Butterflies and Moths of South-Eastern Australia - Pat & Mike Coupar - 1992 - New South Wales University Press
  • Common Moths of the Adelaide region - McQuillan & Forrest - 1985 - South Australian Museum
  • Butterflies - Dick Vane-Wright - 2003 - The Natural History Museum, London
  • Some Observations on the Eggs of Moths and Certain Aspects of First Instar Larval Behavior - Noel McFarland.-Journal of Research on the Lepidoptera 1973 - Vol 12(4): 199-208
  • Egg Photographs Depicting 40 Species of Southern Australian Moths - Noel McFarland.- Journal of Research on the Lepidoptera 1973 - Vol 10(3): 215-247


Parasites of Caterpillars

Population Control

Given that some moths can lay many thousands of eggs, we can be glad that there are many ways by which the lepidopteran population is regulated. Predation by birds and small carnivorous mammals have a major impact on numbers.

In a healthy eucalypt woodland, birds can take about half of the insects produced (some 30 kilograms per hectare per year) and small mammals (bats, sugar gliders, and so on), predatory insects and spiders take a substantial proportion of the rest.
Salt, Lindenmayer, & Hobbs - (2004)

Aside from predators, there are also things like fungal and bacterial attack to contend with. One well known bacterium, Bacillus thuringiensis, marketed under names like Dipel, is regularly used by gardeners to control caterpillars.

Anyone who has had a go at rearing caterpillars, will also be well aware of the many parasites of caterpillars such as mites, wasps, and flies. While it can be disappointing for a rearing project to have been parisitised, it is also quite fascinating to get a close up view of these natural population controls in action. Below is a brief look at a few of the parasites I've come across.

Mites

Erythraeid mites are the most common ectoparasites of moths and their larvae. (Ectoparasites are those which feed externally on there host.) These do not kill their host. The six legged mite larvae gorge themselves on the blood of their host. When finished feeding they drop off in order to complete their development into the eight legged adult stage.

The photos below shows red Erythraeid mites on Uraba lugens (Gum leaf skeletoniser).


While your there, have a look at the little hats the Gum leaf skeletoniser wears. Each time they shed their skin, a bit of the dried skin and the old head capsules do not detach and so they pile up like little hats.


Parasitoids

Unlike ordinary parasites, Parasitoids eventually kill their host. They feed on the less vital organs at first. Common parasitoids of Lepidoptera include Ichneumon wasps, Braconid wasps and Tachinid flies.


Ichneumon Wasps

Ichneumonidae is a very large family of parasitic wasps with around 2000 species in Australia and about 120 of these found in Tasmania. They attack not only several insect orders but also spiders.

Pupation can take place either within the host or it may exit the host first and make it's own cocoon on vegetation or among the leaf litter. The next shot shows an exit hole where dozens of small Ichneumon wasps have emerged from the pupa of Pieris brassicae (Large White Butterfly) These ones have emerged as adults having pupated within the butterfly pupa. (Note: The 4 photos relating to Ichneuman wasps were taken in Scotland)




With larger species of wasp there may be just one egg laid in each caterpillar. For example, here is an arctiid pupa which had a single large Ichneumon wasp emerge from it.


Braconid Wasps

Another major family of parasitic wasps are the Braconidae. They belong to the same superfamily, Ichneumonoidea, as the Ichneumonidae. Australian has about 800 species of Braconid wasp and at least 52 of these are found in Tasmania.

Braconids parisitise insects from many different orders including the Lepidoptera. The female generally lays eggs in the host larvae although sometime they are laid in the host insects eggs. In rare case adult hosts are attacked. Braconids are usually internal parasitoids (Endoparasitic) although some feed externally (Ectoparasitic).

Some Braconids will pupate within their host although more generally the larval grubs will exit their host first. Below is a photo of some Braconid wasp pupae. They had eaten there way out of the caterpillar and immediately made their silk cocoons.



Braconid pupae shortly after exiting an Arctiid caterpillar

Tachinid Flies

There are over 540 species of Tachinid fly in Australia with around 125 of these found in Tasmania. The larvae of these flies are parasitoids of other insects from several insect orders including Odonata, Hemiptera, Coleoptera and especially the Lepidoptera.

The flies generally lay there eggs on, and sometimes in their host. Others will lay the eggs on plants where the will either be ingested by the host or else hatch first and then find their way onto their host. The photos below show two, of three flies along with an empty puparium. These came from an Arctiid caterpillar. In this case the fly larvae, each only 4mm in length, exited the caterpillar prior to pupating leaving behind the shriveled body of the caterpillar.


An Arctiid caterpillar after being parisitised by Tachinid flies


The Tachinid flies and a pupal case


References:

  • Common I.F.B - (1990) - Moths of Australia - Melbourne University Press
  • CSIRO - (1991) The Insects of Australia - A Textbook for Students and Research Workers; Volume 1 & 2; Melbourne University Press; Carlton; Australia
  • Salt, Lindenmayer, & Hobbs - (2004) - Trees and Biodiversity - A Guide For Australian Forestry
  • Semmens, McQuillan, Hayhurst - (1992) - Catalogue of the Insects of Tasmania -
  • Zborowski & Storey - (2003) - A Field Guid to the Insects of Australia


  • BYO Beetles

    BYO - Not "bring your own" but "breed your own" beetles. For anyone interested in learning more about invertebrates you may want to try rearing beetles and observing their life cycle. Oh and I know this is not specifically related to Tasmania but it is a convenient test for my first use of this blogging software.

    Tenebrio molitor - (Mealworm beetle or Darkling Beetles)
    • Order: Coleoptera
    • Sub-order: Polyphaga
    • Superfamily: Cucujoidea
    • Family: Tenebrionidae
    This Mealworm Beetle (Tenebrio molitor) is one of the largest Tenebrionids with adults at 12 and 20 mm. It is considered a commercial pest of stored grain and grain products. However, the larvae, or mealworms as they are known, are often bred and sold for feeding fish and wild birds. As they are readily available in many countries they are a great species to observe the beetle life cycle.

    We ordered ours over the Net and they arrived safely packaged overnight. We kept them in a small plastic fish tank with a layer of oatmeal and bran for food. An apple cut in half an placed face down as seen in the photo, should provide enough moisture.

    Obviously the apple will need replacing and the food topped up as needed. A fine mist spray could be used but be careful. Mealworms are built to tolerate very dry conditions. Too much moisture could lead to fungal infection.



    All Coleoptera (Beetles) experience a complete metamorohisis, also called holometabolism, which includes four stages; the egg, larva, pupa, and imago(adult). When our mealworms arrived they were already well along in there larval development. As any arthropod grows it needs to moult or shed it's skin. The periods between each moult are known as instars and in the case of mealworms they go through about 15 instars.

    Here is a photo of a mealworm:

    ..... and another which is in the process of moulting. When they first moult they appear white but within a day or so they take on the golden brown colouring.



    A week after receiving the mealworms some were already passing through their final moult into the pupal stage. This next image shows the final larval moult.



    ....and here is a ventral view of the new pupa.


    I removed the first four and kept them in a seperate container so that I could time their progression into adults. The next photo was take six days after pupation.

    On day ten, the beetles emerged which was sooner than I had expected. The emergence process took about 20 minutes.


    Notice the beetle has not yet attained its mature colouring. It is also still quite soft. This stage is described as the teneral imago.



    Over the next couple of days they gradually darken and harden until reaching a dark brown, almost black, colouration.


    Four days after emergence I've noticed the first interest in mating.

    ....and so the cycle continues.