Assassins on the prowl

We have spent the last three months filming a TV series on predatory bugs, and some of the predators we have been working with are the assassin bugs. They are incredible insects that hunt by stealth, then stab their victims with their long proboscis and paralyse it within seconds.

Watching them hunt is amazing. Once they detect prey they will approach it with such caution that they hardly seem to be moving at all. All the while they keep tabs on their intended prey with extremely long mobile antennae. Sometimes the strike is rapid, but other times they try to sneak in a little lethal injection without the victim noticing. Once the victim notices the little sting it is all but over. The assassin bug then feeds on the victim via its proboscis, and discards the empty husk when finished.

 

A delicate orange assassin bug from our garden. This species is a ready flyer.

The same species feeding upon a grasshopper.

One of the giants, a Bee Killer Assassin Bug Pristhesancus plagipennis found about 10 minutes west of Kuranda

A close-up of the proboscis of Pristhesancus plagipennis. This species can capture very large insects.

Mini ambush hunters

Both these tiny spiders are hunting in our front yard. The yellow crab spider (Thomisus spectabilis) is a flower-top hunter. This species waits in ambush for flower-loving insects. They can catch prey up to the size of a honeybee, many times their own size.

Crab spider, Thomisus spectabilis. Crab spiders are so called because of their ability to move sideways.

The Triangular spider (Arkys sp.) is another ambush hunter which sits and waits upon leaves for passing prey. Although these two spiders are unrelated, they both share similar adaptations to assist them to snatch and hold their prey.

Triangular spider, Arkys lancearius

Nocturnal visitor

We were returning from a recent night walk, and had practically reached our front gate when we had a chance encounter with another invertebrate lover. This one, a Striped Possum (Dactylopsila trivirgata), prefers to eat the invertebrates it finds. Striped Possums have an elongated 4th finger and use it to hook out wood eating grubs from within the trees. They also use their teeth to tear open the timber to expose the insects. The diet of this species is not just confined to insects, they also feed upon fruits, leaves, and will dine out on the honey of native bees if they are lucky enough to find some.



The Striped Possum just opposite out driveway. It dissapeared very quickly after this photograph. 



Bright orange amongst the green

It seems that being bright orange and yellow is the recipe for success in the rainforest for several species of Australian huntsman spiders. Compared with the grey-brown camouflage colouration of most of the southern species in the Sparassidae family, many of the rainforest huntsmen are simply stunning.

This week I have encountered two brightly coloured species in the genus Beregama. Beregama cordata, the Fireback Huntsman, and Beregama aurea, the Golden Huntsman. The latter is a huge spider and is considered the second largest species of huntsman in the world behind Heteropoda maxima from Laos.

Previously in this region we have encountered the orange/yellow Sunburst Huntsman and the Tiger Huntsman, both of which are undergoing classification.

Why bright orange? As juveniles these spiders are quite dull and cryptic, but they progressively adopt the brighter colouration as they grow. As adults, they often stand out like beacons within their habitats. Whether the colours are just for warning away predators or for some other purpose I cannot say. It does not seem likely that it is for courtship purposes as the vision of this group is quite limited, and courtship seems based upon pheromone detection and tactile interaction.

 


A huge male Beregama aurea, 4km west of Kuranda

 

A female Beregama cordata at Cape Tribulation

A Sunburst Huntsman from Cape Tribulation in 2006

The female Tiger Huntsman we found near Cairns in 2006. (This was the first record of this species and is currently at the South Australian Museum awaiting description)

Spider identified and mantispid emerges

We have identified  the crab spider as Poecilothomisus speciosus (thanks Colin). It is the sole member of the genus in Australia, and is only found in north eastern Queensland. We are not sure why the Australian spider has been placed in a genus by itself, whilst the related overseas species are all members of Platythomisus - had me confused.

Today the eggs hatched but only a handful of tiny spiderlings emerged from the egg sac. The reason for this was because an invader had also been occupying the egg sac - a mantispid.  Mantispids are mantis-like Neuropterans and some species select spider eggs as food while they are in larval form. Mantispids use two strategies to access spider eggs; some larvae find an egg sac and burrow in through the silk, while other species hitch-hike upon the female spider and enter the egg sac as it is being constructed. We are not sure which strategy this particular species used, but it was successful.

The mantispid shortly after emerging from the egg sac.

Mystery spider

For the second time in recent years I have swung my torch around to reveal a brightly coloured spider sitting in a tree and knew that I was looking at something very unusual.

In 2006 it was the Tiger Huntsman which turned out to be the first recorded specimen of an undescribed species in the genus Typostola - it is still awaiting description. The fact that you can still find species that are new to science is one of the very exciting aspects of the wet tropics.

This time however, the spider may not be one that is undescribed, but one that is not well documented in Australia. Its movement and body form are clearly that of a crab spider; family Thomisidae. After some sleuth work I have managed to tentatively identify it as Platythomisus sp.. Around 20 species are recorded from Africa, through southern Asia, but apparently not in Australia.

The obvious question beckons: Is this an Australian species or is it an introduced specimen? The plot thickens further as I found this specimen peeking out of a curled leaf whilst incubating eggs.

I will endeavour to contact an arachnologist who has experience with Australian Thomisids to answer this one. Stay tuned!

The specimen is quite large compared with the majority of Australian Thomisids. Body length 14mm.

The markings on this specimen are quite stunning and are very similar to Platythomisus spp. found throughout Asia. It does have distinct differences though.

For a small spider it is quite aggressive and actually tried to bite my finger whilst I was taking these photographs.

One of the first things that struck me was the superficial resemblance to the spitting spiders Scytodes. Interestingly, one species of Platythomisus has been named P.scytodimorphus

Daylight robbery

This stunning fly is one of several species of Robber flies (Family Asilidae) that are active at the moment around our home. Robber flies are active hunters that catch prey in flight, or pluck it from foliage. They have huge eyes, excellent vision and a capacity to turn their heads rapidly to keep track of prey or threats. They feed through a large proboscis which is driven into their prey to extract its body fluids. Some species are nocturnal and we have observed them feeding on large cockroaches, but the species below is active by day. Robber flies will often fly short distances and return to the same area to wait and watch for potential prey, making them reasonably easy to observe and photograph.

This Robber fly is feeding upon a blowfly

Sun lover

Cockroaches aren't usually associated with sunbaking, however cockroaches in the genus Elipsidion are renowned for basking in the sun during the day. They are spectacular cockroaches with vivid markings, some even have transparent window-like areas in the pronotum. I photographed this specimen soaking up the rays in the dryer country west of Kuranda. It is a young specimen (a nymph), and will have fully functional wings once it matures. These cockroaches inhabit the foliage of various plant species, and most likely feed upon pollen, honeydew and fungi.

Our porch visitor

To our delight, a Yellow-bellied Sunbird, Nectarina jugularis, has made its suspended nest right next to our rear patio door. This species is a small nectar feeding bird, only 10-12cm in size. We were able to watch the bird produce its nest from the very early stages; the bird returning every minute or so with more building material. Once the pendulous nest was completed, the soon to be mother settled in and we have only seen glimpses of her through the nest’s small circular opening.

Yellow-bellied Sunbirds lay 1-2 eggs with an incubation period of 14 days. Young fledge 15 days after hatching although the survival rate for nestlings is only around 20%. Two nights after the nest was built we were awoken by a terrible shrieking sound coming from the nest. We suspected a Brown Tree Snake, Boiga irregularis, was attacking the bird, but upon inspection no such predator was present. The Sunbird has since been seen in her nest so everything appears normal again. We can only wait and see what happens and wish her luck.

The Yellow-bellied Sunbird halfway through nest construction

Experts in camouflage

One of the largest and most common katydids in northern Queensland is also one of the most seldom seen. The Spiny Tree Katydid (Phricta spinosa) has excellent camouflage and positions itself motionless on tree trunks through the day to avoid detection by visual predators. The specimen pictured below was beside a rainforest walking track, where I witnessed tourist after tourist wander by within 40cm of the katydid looking for nature, but obviously not looking hard enough...

The Spiny Tree Katydid resting on a small tree adjacent to the walking track.

A close-up of the head of the katydid. The spines, colour and pattern all help to break up the outline of the animal resulting in excellent camouflage.

Eight legs beats thirty

On a recent field trip to collect house centipedes (Scutigeridae) for the filming project we are working on, I found a large specimen but not quite in the way I expected. This one had just been caught by a Brown Huntsman (Heteropoda sp.) and probably wasn't going to be much use to us on set! These centipedes have 15 pairs of long thin legs, and needless to say they move very fast. As quick as huntsman are, it is still surprising that it managed to catch such a sensitive and rapid moving animal.

House centipedes have two large compound eyes contrasting with other groups of centipedes which have smaller simple eyes. They are predatory and venomous, injecting their venom through short modified legs which act as fangs. These 'venom claws' are located just below the mouths of house centipedes.

The name 'house centipede' originated overseas due to some species occurring inside houses. Ironically most species of house centipedes never come inside.

The Brown Huntsman (Heteropoda sp.) feeding on the house centipede.

A specimen we found a couple of nights later at the same site. This species can attain a body length of almost 60mm with a leg span of over 100mm.

Forest jumpers

The northern tropics are home to a diverse array of jumping spiders (Salticidae). These relatively small spiders are diurnal and are extremely active hunters. They visually locate their prey using their eight eyes which are spread around their heads. The two large anterior eyes provide the spiders with particularly good vision and allow them to judge distances accurately. Most species will stalk prey to within their preferred strike range then leap on it with a great burst of energy. Some species can leap up to 30 times thier body length. Many species will attack prey up to, and sometimes beyond their own body size. Here are a handful of species we have encountered so far.

Now you see me...

After assisting our neighbour at BatReach with an unwelcome visitor (a 3m Amethystine Python) I was walking back home and spotted an unfamiliar katydid perched on top of a leaf. As soon as I inspected more closely the katydid flattened out in umbrella style, concealing all its typical insect features. The katydid in question appears to belong to be Acauloplacella sp. but I'm waiting on confirmation from katydid guru David Rentz. These katydids have superb camouflage, the wings resembling the leaves they reside in with almost exact venation.

The katydid in its active posture.

Hidden beneath its wings.

Gecko crossing

I found this gecko in the middle of a small road through the rainforest while returning from a recent bug trip north west of Kuranda. It's a Chameleon gecko (Carphodactylus laevis), a very large and unusual species, and sole member of its genus. It is nocturnal like most geckos, and forages through the leaf litter for prey. It has a remarkable defensive strategy. Initially the tail is waved if the gecko is threatened by a predator, but under severe duress the gecko will drop its tail. The tail not only continues to wriggle and writhe to distract the predator, it actually makes a noise. An area on the broken section of the tail opens and closes with each movement, and the sound resembles the distress call of a young rodent. Meanwhile the gecko makes its getaway, and can regenerate a new tail within six months.



The Chameleon gecko (Carphodactylus laevis), after I released it away from the road.



Cape Cassowary

On Sunday we travelled up to Cape Tribulation, about a 2 hour trip from home. We dropped in to the Cape Trib Farmstay to say hi to the people who we've stayed with while on the Melbourne Museum field trips each year. It was extremely wet there - they've only had half a dozen days when it hasn't rained this year. Not good for their fruit.

Late in the day we talk a walk on the boardwalk and spotted a handful of bugs including a 'squirt' of Peppermint stick insects.

The Peppermint stick insect (Megacrania batesii) feeds solely on Pandanus sp. and has the unique ability to spray a  strongly peppermint scented liquid at any threat that approaches too closely. If the spray gets in your eyes it can cause extreme irritation.

The highlight of the day though was an encounter with a wild Cassowary and his very large chick. We came across them while on the boardwalk, and had the chick on one side of us and the male on the other. This made us a little nervous at first, but we remained very still and he did not seem perturbed at all. At one point he joined us on the boardwalk only metres from where we stood transfixed.

Venturing west

On Wednesday night we took a little trip west to see what was out and about. You don't have to go far to see dramatic changes in the landscape and habitats. One moment you are driving through rainforest, the next you are in open woodland dominated by eucalypts and acacias. Light sheets were set-up by David and Buck who were in search of moths in particular, while I spent most of the evening direct searching for invertebrates and other wildlife on the ground and within the foliage and tree trunks. I wasn't disappointed.

A Lycosid (Wolf spider) looking out from her burrow.



Juvenile Ornate Burrowing Frog, Opisthodon ornatus.



An unusual orb-weaving spider, another species I have encountered for the first time.

The find of the night for me was yet another spectacular huntsman spider. Not quite as colourful as the Tiger Huntsman we found in 2006, but incredibly, even larger. The seven-legged adult female easily spanned my hand, and like most huntsmen she moved like lightning. I've identified her as Beregama aurea, one of four species in the genus. Two are found in Papua New Guinea, and two within Australia. The other Australian species is Beregama cordata which we have been keeping and breeding for several years. They are rainforest species and we have found them near Cairns, Kuranda and Cape Tribulation.

We have set-up this new specimen in a large terrarium and have been feeding her a steady supply of moths and cockroaches. She has an insatiable appetite so we are hoping she has been mated and will produce eggs.

The seven- legged 'Golden Huntsman', Beregama aurea

What lovely eyes she has! She is a relatively old specimen, evidenced by her buffed and hairless cephalothorax.

Destination Melbourne Museum

The Green Ant display in Bugs Alive! at Melbourne Museum has been desperately in need of a new colony for the last couple of months. We collected the last colony in December 2009 while on a field trip in north Queensland. That colony survived well for several months but then produced vast numbers of reproductives (new queens and males). This is usually a sign that a captive colony is reaching the end of its life - and that turned out to be the case. Despite our attempts to encourage the new queens to mate with the winged males, none were forthcoming and only infertile eggs were laid.

We have just harvested a new colony for Melbourne Museum's display from our backyard. Four individual silk-bound nests were collected from a passion vine and sent via Express Post. The ants are now happily constructing new nests within their very public home in Bugs Alive!

One of the Green ant nests that made the journey

The ants on full alert  - what is that strange man doing with a pair of secateurs and a bucket.

Green ants are fascinating in many ways. One unusual aspect of  their behaviour is the use of their larvae as tools - the larvae produce silk. The worker ants hold the larvae in their mandibles and use their silk producing siblings to bond leaves together to form nests. This occurs whilst other patient ants hold the leaves in place. This laborious process can take several hours.

More life around the yard

There's always something happening in the garden here, and the great thing about moving to a new area is that there are so many new things to encounter. So far we have seen at least half a dozen species of jumping spiders (Salticidae) in our yard. Today we also spotted a colourful diurnal cockroach (Ellipsidion sp.) out enjoying the sun.

One of many jumping spiders active in the sunshine.

Another just passing the time. 

Ellipsidion sp. These cockroaches are colourful and active by day, not at all stereotypical cupboard dwellers.

Malanda walk

Went to Malanda yesterday, a small town south east of Atherton in north Queensland. Went for a walk in on 1km rainforest loop before and after dark. The cicadas began calling just on nightfall and were literally deafening, the combined sound from the thousands of calling insects was brain piercing and at distortion point. After about 15 minutes someone amongst their ranks decided enough was enough and they all became silent. That left the night to the more pleasent calls of crickets and katydids.

Although its early in the season, there's a bit of life starting to appear. Two Boyd's Forest Dragons (Hypsilurus boydii) were out before dark along with an abundance of strange flies including some crane flies with legs 80mm long. After dark White Kneed King Crickets (Penalva flavocalceata) were very active, and some very large harvestmen were present on tree trunks.

A Boyd's Forest Dragon. This one was sitting motionless just off the track.

Some strange flies displaying even stranger behaviour. They were facing off, then creeping towards one another. As I took the photo the one on the right stooped down to drink at the foot of the other.

Another species of rainforest fly we are not yet familiar with.

A large Harvestman; an arachnid with eight legs and a single body part - spiders differ as they have two distict body parts.