Day 6: Slightly Social Wasps, Frogmouths and Blind Running Beetles.
Myrmarachne sp. ant mimic jumping spider.
Ted slept for a solid ten hours after I read him a bedtime story and woke feeling a fair bit better. Just to be sure, we decided to have a relaxing day and spent most of the morning identifying many of the animals from the photos taken over the last few days. Ted was given a dead snake in a bottle to ID to keep him happy by Agus Din.
Bottle snake Amphiesma sp. potentially sarawacense.
However, it was not long until the pull of insects away from my camera’s screen began to pull my attention. Behind us in the leaves that were looking into the lodge stood a stick insect, slowly swaying in the wind. It has been shown in experiments that this swaying movement of stick insects in the wind is not incidental and is, in fact, purposeful wind mimicry by the insect to fool predators. The researchers showed that the insects were able to accurately mimic the frequency of the branch’s own sways in the wind to better blend in. (https://academic.oup.com/beheco/article/27/1/83/1742619).
A small black and yellow blur scooted past me. Viewing it as the final straw for sitting down, I bounced up and followed it to near a doorway. It was one of the hover-wasps in the Hymenopteran sub-family Stenogastrinae. This one was a Parischnogaster species and was a queen just beginning to make her nest. These wasps are primitively eusocial (any colonial animal species that lives in multigenerational family groups in which the vast majority of individuals cooperate to aid the relatively few (or even single) reproductive group members) and have been used as proof that eusociality evolved not once, but twice in wasps.
The eusocial paper wasps (Polistinae) and Vespinae wasps (this includes the yellow and black common wasp we see regularly in the UK) are quite different to the hover wasps (Steogastrinae) but far more similar to the solitary Eumenid and Masarinid wasps in terms of their molecular genetic data (see quick sketch of their phylogenetic tree).
Phylogenetic tree of the dual evolution of sociality in wasps.
The Polistinae and Vespinae wasps differ in their eusocial traits to the Stenogastrinae hoverwasps in the following ways. The Stenogastrinae lack the true worker and queen castes found in the other groups. All three groups feed their young as they grow older but the Stenogastrinae feed them far less often than the other two, often just once a day or less. Furthermore, how the wasp groups build their nests is very different. The Stenogastrinae nests are much smaller (usually no more than ten adults) than the nests of the other species and this small colony size is thought to be a limiting factor as to why the Stenogastrinae were not globally successful in comparison to the other groups as the small colony size meant that there were simply not enough individuals to fill all the roles of eusociality.
Interestingly however, this genus of hover wasp (among some others) Parischnogaster is capable of camouflaging its nest in order to protect it from any predators. If it is built on a smooth surface, the nest will be smooth and rough if it is on a rough surface!
The males are quite territorial creatures and will have a favoured perch which they hover near. They will occasionally flash shiny bands on their abdomen, trying to attract females to their perch so he can mate with her.
After watching the fascinating little wasp for a while, I decided that I needed to get outside and hunt. Leaving Ted to ID his bottled snake (which he eventually managed: Amphiesma sp. potentially sarawacense) I grabbed my net and camera, promised Agus Din I wouldn’t go too far into the jungle alone, and set off.
Reaching the reservoir one of the first things I found was a lynx spider, Oxyopes lineactipes. These spiders are cursorial and so actively hunt without the need for a web. They have good eyesight and rely on sight and speed to capture their prey. They are also covered in short spiny hairs. It is thought that these hairs are used by the spider as a cage to trap more agile prey. These spiders are generally quite skittish to anything bigger than them and quite aggressive to anything smaller. However, apparently when they meet other lynx spiders in the same species they are quite friendly and often meet in small groups, although I am not sure as to the reason why. There is one lynx spider in the genus Tapinillus that is fully social and feeds and lives together with other spiders in the same species and so, as evolutionary time progresses, perhaps more lynx spiders will become social.
Oxyopes lineactipes lynx spider.
While glancing into the dead leaves of a creeper slowly moving its way up a trunk I noticed a tiny movement of grey. It was one of the amazing ant-mimic jumping species, this one being in the Myrmarachne genus which is one of the most diverse. Males like this one have enormously enlarged chelicerae (fangs) giving them the appearance somewhat of a soldier ant. The females lack these large chelicerae and so look slightly more like workers. This spider will wave its front pair of legs in the air in an attempt to mimic the antennae of an ant. On this species you can just about see tiny false ‘segments’ on its legs to mimic the antennal segments of an ant! It is generally believed that by copying the physical appearance and behaviour of ants, these ant-mimicking jumping spiders are actually buying insurance for self-protection. This is because spider hunting predators will generally avoid ants which secrete the distasteful formic acid when attacked.
Myrmarachne ant mimic spider.
Alongside the formic acid, some ants are extra protected like this Polyrachis species of ant with its spiny thorax. These spines have likely evolved to stick in the throat of predators like birds.
More ants were crowding around spots of honeydew on a nearby plant, sipping the sweet liquid to take back to their nests. As I watched, a tiny bee flew in and began to feed as well. It was a stingless bee, Trigona sp., similar to those nesting outside our front door in the lodge but a little bigger. These bees, as their name suggests, have no sting and instead can only secrete a sticky fluid. This bee stayed a little while collecting the sugary honeydew before yielding to the attentions of the fairly cross ants and zipping off.
Trigona sp. stingless bee.
I had reached a dry area of sandy soil on the corner of the reservoir and could see small green jewels buzzing about my feet. Getting down on their level I could appreciate the rainbow colours of the tiger beetle Cosmodela aurulenta. These beetles move so immensely fast that they can cover 120 body lengths every second. They also have incredibly sharp vision but because they move so fast and their vision takes up so much energy, they can only see a blur when running at full speed and can no longer see any obstacles or even the quarry they are chasing.
Now this may seem like an evolutionary disadvantage, how can something still catch food when it loses sight of the prey as soon as it starts running? The answer for the tiger beetles is simple: just run so fast that you can afford to stop mid chase, reassess and still catch your prey! However, the beetles have a further problem: how to stop tripping over or running into things? A researcher named Daniel Zurech at the Cornell university has worked it out by observing that the beetle is permanently in ‘collision mode’. The beetles hold their antennae out in front of them as they run and they hold them completely still. This means that the antennae work as obstacle detectors. If they hit an object the antennae bend, sending signals to the beetle’s brain which in turn angles the beetle slightly upwards. While the beetle cannot avoid the obstacle at full speed, by angling its body it can ensure that it skitters over the obstacle rather than bouncing back off it. Zurech went slightly further when testing this and found that as long as the antennae are intact, the beetles would not be hampered by obstacles, even if he painted over their eyes!
Cosmodela aurulenta tiger beetle.
A small black and yellow insect caught my eye as it alighted on a leaf. Moving forward with my camera, it was only as I looked through the magnified image of my macro lens that I realised the wasp was carrying a small leaf hopper. Similar to many UK wasps, this one had caught the leafhopper, paralysed it and was now taking it back to her burrow in order for her young to feed on. Interestingly, many wasp larvae that feed on paralysed animals eat in a very specific way. They start with the least important organs and end with the most vital, thus keeping the poor prey alive for as long as possible so it remains fresh and good to eat.
Wasp and paralysed prey.
Swinging my net, I caught a tiny beefly most interesting because it was almost completely black save for a clear patch on each wing. Presumably having a similar life cycle to the larger more showy Ligyra tantalus from day 3 (??) I almost preferred the more clandestine fighter-jet styling of this species.
Before heading back to the lodge I also found another ant mimic spider in Corinnoma severum and got some more photos of the extremely pretty eyes of the male Oriental latrine fly.
Corinnoma severum spider.
Male Oriental latrine fly.
Just as I was turning around I heard the deep buzz of a Xylocopa latipes bee and jerked my net up to catch it as he barrelled past. Realising I had failed to get a good size comparison shot earlier, I wrangled it into a large pot and took this photo on my phone before he got too cross and had to be released.
Big Xylocopa latipes bee.
Ted was still feeling a bit ill after we had lunch (it was mostly me having the lunch) and wanted to be fit for the night walk and so declined my offer of a short afternoon wander. I headed down into the forest behind the lodge to see the pitcher plants that we had found a couple of nights ago. I decided to take my little Mr Garden Figure with me. Mr Garden Figure is a playmobil man who was discovered in my garden during my GCSE’s and had lots of adventures: see here… https://tinyurl.com/MrGardenFigure
He had a fairly unfortunate time as he was almost swallowed by a pitcher plant while looking for a specific crab spider that only lives under the rim of the plants before feeling better watching the intricacies of termite trails.
Mr Garden Figure getting to know a pitcher plant rather too well.
Mr Garden Figure likes termites.
After tea Ted began to feel much better, helped no end by the chance of finding even more herpetile species on the night walk.
The humidity was still high as we left the lodge as the moon began to rise. Ted, back to his chirpy enthusiastic self, was asking whether we thought that tonight would be a good night and I was just about to reply when I noticed a dark shape sliding through the grass. Flicking on my torch beam we saw that it was not dark and in fact banded black and white with a red/orange head. ID’d by Ted as an Orange lipped water snake (Macropisthodon flaviceps) which is a fairly uncommon semi-aquatic creature almost exclusively found in lowland boggy areas. Apparently it is quite an angry snake that, although lacking in potent venom, will puff up its neck if threatened. We didn’t get to see this however as it quickly slithered off into the darkness.
Our first insect of the evening was a beetle in the form of Pleuronota elongata. This beautiful painted scarab is one I know so little about other than its name. Please excuse the muddy nails, very hard to remember to clean them when continually hunting in the jungle.
Agus Din suddenly stopped on the boardwalk as we were walking into the jungle. He had spotted a bird fly into a tree about 20m away and swung his powerful torch onto it. It was one of the birds we had been hoping to see, a Sundan Frogmouth! This is one of the smallest frogmouths in Borneo and has an excellent hunting strategy which Ted, who knows far, far more about birds than me, explained. Frogmouths are very closely related to nightjars (which you may have seen and heard in the UK if you are lucky) but have a vastly different hunting strategy, some may even say the least sophisticated out of all the nocturnal hunting birds. They simply sit on low bare branches at night (generally 1-2m high) and stare at the ground, waiting for an unsuspecting animal to pass below. Their prey ranges from large insects, rodents to lizards, frogs and even snakes. When they spot something to eat they simply drop on it, big mouth open, and swallow it whole!
One of my favourite things about the jungle at night is how easy it is to spot spiders with their eyeshine from torch beams. If it wasn’t for the tiny pinpricks I would never have noticed the juvenile Sparrassid (huntsman) spider clinging to the underside of a dead leaf. Blending in almost perfectly this spider, although a young one, was still palm sized with legs and was likely a David Bowie huntsman (Heteropoda davidbowie) so named because of its facial markings… Really hoping to see an adult as they are immensely pretty animals.
Juvenile Heteropoda davidbowie.
Some spiders do look a little more sinister than others and the dark form of Parawixia dehaani is one of those such spiders. This spider is an orb weaver and so makes a large web. It is highly variable in its colouring for reasons unknown to me. (We find a really cool looking one tomorrow!).
Following a few glistening strands of silk spun horizontally between leaves led us to another, smaller spider. It was fairly round with the armoured covering we had come to expect from the Macracantha type spiders (see day 2) but shinier. Further research when we got home led to its ID as a spider in the Cyrtarachne genus. However, the most amazing feature was the shape of its web. It consisted of three main strands starting wide apart and running horizontal until converging to a point on a tough stem forming a triangle shape. Between each strand hung looping hammock threads so the final construction looked a little like two half cylinders of glistening silk hammocks starting wide before narrowing together into a point.
Interesting web of the Cyrtarachne sp. we found.
Research by Claire Cartan and Tadashi Miyashita in 2000 showed that the silk of the Cyrtarachne species has amazing properties. The strands are up to four times thicker and able to withstand seven to ten times the amount of force the silk of other spider genuses can. Interestingly, the amount of force the silk is able to withstand is very similar to the amount of kinetic energy a moth exerts while it is flying. It is extremely likely that the silk of these spiders specifically evolved to be able to hold flying moths. The spider’s web is horizontal so as not to obstruct the moth’s flight path entirely and also for protection so if the moth collides it will not destroy the whole web. Each of the strands hanging down in the hammocks are very sticky and if the moth brushes one it will become ensnared due to the strength of the silk strands. Because the web is horizontal, it is possible for multiple moths to be caught without destroying the web, giving the small spider lots to eat!
Ted spotted another leaf mantis on a tree in front of us and I rushed forward, shutter clicking not wanting a repeat of day 4’s complete miss of the most beautiful dead-leaf mimic mantis. This one was quite incredible in its camouflage but unfortunately not as good as the one we saw and missed a couple of days ago. The one that got away often seems better in retrospect.
Leaf mimic mantis.
There are lots of big huntsman spiders here in the jungles of Borneo and very few are prettier than the big, flat lichen huntsmen (Pandercetes sp.). These spiders lie flat on the trunks of trees and blend in beautifully with the lichen on the bark. Like the other huntsman spiders they are sit-and-wait hunters, hoping for smaller prey to wander unsuspectingly past.
Pandercetes sp. Lichen huntsman.
Although a huge fan of all things dangerous and will rarely hesitate to pick up venomous snakes to handle them with skill, there are some animals in the jungle that make even Ted nervous. One of these is the especially leggy Scutigera centipede. These can grow to about 20cm long and have an extremely painful bite. When they run they look as if they are gliding over the surface, propelled by a cloud of legs. Their long legs are not only for moving quickly however, as their back limbs will very easily break off in a predator’s clutches, allowing the centipede to escape. They have huge antennae too to find their way and their food in the jungle gloom. I must say that I am quite keen on these less-loved animals.
We had come to a clearing and while Ted and Agus Din listened and hunted for the elusive large frogmouth and wood owl, I wandered about looking for big spiders on tree trunks. About four metres above my head I spotted one of the rarer ones: a twin tailed bark spider, Hersilia sumatrana. These spiders have a fascinating prey capture method. They are very well camouflaged to their chosen tree (I only found this one due to its eyeshine) and will lie flat against it. Instead of making a web to capture the prey insect directly, the spider lays a light coating of threads across an area of tree trunk in front of it and waits. When an insect walks over the area the spider spins around, directs its oversized spinnerets at its prey (giving the spider its twin-tailed namesake) and circles the insect, spraying as it goes. Once the poor insect has been completely immobilised the spider moves in for the kill, sinking its teeth through the insect’s new silk coat.
Beginning the journey back, I was at the back of our little trio and was called forward by Ted and Agus Din to see their latest find. On a branch about 7 foot above the path was an emerald green bird with a black head, resting and completely oblivious to our presence. It was a hooded pitta and was not all that common. They are ground feeding birds and forage for insects mostly but the occasional berry too. As we moved closer it opened its eyes but obviously wasn’t confident enough to fly away in the gloom (or just didn’t see us as much of a threat) and so allowed us to take my only vaguely acceptable bird photo of the whole trip!
Hooded pitta ft. Ted.
For the last few night walks we kept seeing massive ghostly moths floating off into the darkness. One especially big one flitted across the track in front of me. Seeing it as somewhat as a taunt I crashed off through the jungle after it, willing the big moth to land so I could get a photo and ID it. Eventually the large Lepidopteran sat on a leaf for a few moments allowing me to get a photo and for Ted to ID it as a Lyssa menoetius.
Lyssa menoetius moth.
While some spiders here are big, the harvestmen are bigger. They are arachnids but not true spiders as their head, thorax and abdomen are fused together whereas the true spiders have separated cephalothorax and abdomens. Some of harvestmen here have extremely long spindly legs spanning over 30cm and raising their comparatively tiny body about 10cm off the surface.
Just as we were leaving the jungle I caught some pinpricks of light in my torch beam and almost let out an audible gasp as I investigated their source. It was a very orange David Bowie huntsman (Heteropoda davidbowie) and she was looking after her young! This particular female wasn’t as well marked on her face as some of the photos of this species I’ve seen but was incredibly striking with her orange coat. Huntsmen are caring mothers and will look after her egg sac making sure no harm comes to it until her babies are old enough to emerge. Her spiderlings will remain with her for a couple of days until their first moult until they feel big enough to go off and survive in the big world by themselves.
Beautiful David Bowie huntsman female with eggs. Heteropoda davidbowie.
Walking out of the jungle, along the reservoir and back into the small village we were excitedly discussing what a good night walk it was and how we had managed to see another snake species when we really weren’t expecting to see many at all. We had just said our goodbyes for the evening to Agus Din and wandered into the lodge when he called us back. On his moped was a tiny orange snake! Enthusiastically grabbing it, Ted ID’d it as a barred slug eating snake, specifically Pareas nuchalis! These tiny snakes have huge eyes to spot their prey in the dark and also have lopsided teeth to better winkle out snails from their shells! It was so full of character this little snake that I think it was my favourite reptile from the whole trip. Here is a video not by me (by user Davidsfeed) showing the dramatic chase and capture and demise of an unfortunate snail at the hands of this voracious predator.
Slug-eating snake Pareas nuchalis.
The next morning was our penultimate in the jungles of Sungai Wain and we went to bed determined to make the most of it…