Tuesday, 13 February 2007

#7 Entombed and eaten alive

No, it's not the plot for a Stephen King horror novel. It's nature, and it happens in my backyard (and probably yours) every summer. Caterpillars and spiders are tranquilised, buried alive and then consumed alive by developing wasp larvae.

An orange Potter Wasp working on her mud nest

The two wasps I am featuring here are from different families, but their similarity lies in their choice of nest building material - mud. The Orange Potter Wasp, Eumenes latreilli, is from the family Vespidae and sub-family Eumenidae. The Mud-dauber Wasp, Sceliphron laetum is from the family Sphecidae and is often referred to as a hornet. I am, however, tentative with my identifications as there are approximately 12000 species of native Australian wasps, along with introduced species.

Solitary habits and feeding

Unlike the paper wasps which are social insects, mud-dauber and potter wasps lead solitary lives only seeking out their kind to mate. Adults feed on nectar. I don't have a flower garden so I let my herbs go to seed to provide a few blooms in addition to my vegetables and native shrubs.

An Orange Potter Wasp extracts nectar from basil flowers in my herb garden.

A wasp's tongue differs in structure from that of a bee. A bee's tongue is modified into a long sucking proboscis, while the wasp has to manage with a short flat tongue with attached feelers. The wasp can therefore feed on liquids that are easily reached but is unable to reach concealed or distant nectar.

These two wasp species can often be seen drinking from still water, especially when mud is not available for nest building. I have a water dish buried to ground level amongst my herbs for invertebrates and lizards to make use of.

An Orange Potter Wasp collecting water from the dish I replenish regularly.

A wasp's thorax and abdomen are joined by a slender waist (petiole), and these two wasp species have an extended petiole, as you can see in the next photograph. They have four transparent wings, large eyes and mandibles.

Although they might appear fearsome, these wasps are not aggressive and are unlikely to sting unless attacked or handled. In fact, they almost seem oblivious to the rest of the world as they go about the task of nest-building.

The slim extended waist (or petiole) is a distinctive feature of these two wasps.

Their nest building proceedures are fascinating to observe. And because they are not disturbed by passive on-lookers, they can be easily observed, even by children.

Mud nest construction

Unlike bees, no workers are produced, so individual nests are constructed by females. It is a massive project with differences in construction style with each wasp species.

The Orange Potter Wasp assembles flattened circular brood chambers about 25mm wide leaving a hole in the centre. The common name of potter wasp characterises the neat clay-pot appearance of the individual chambers. Both wasps will attach nests to exterior walls of buildings or most surfaces that are protected from moisture. Open sheds are particularly popular building sites and they have been known to clog up motors or machinery that remain idle.

A Potter Wasp has filled a chamber with caterpillars.

In the top picture, you can see the wasp's large mandibles separating a blob of mud into workable sized portions. It's hard to imagine just how many trips to the mud puddle the wasp must make in order to complete 7 or 8 chambers and then render the nest with several more layers. If mud is not available, the wasp will collect water and then dig soil to make its own mud.

The nest pictured above was destroyed and raided by a black rat, the introduced Rattus rattus, the night after this photograph was taken. No doubt the wasp would have rebuilt elsewhere.

A Mud-dauber Wasp putting the finishing touches to a cell after completing and rendering three chambers the previous day

The Mud-dauber Wasp, Sceliphron laetum, builds long narrow breeding cells with an opening in one end. The wasp will temporarily seal the chamber if unable to fully stock it before nightfall, removing the capping when it returns to finish construction.

Feeding the young

The female wasp has a sting which she uses to render pray helpless. The potter wasp collects caterpillars, while the mud-dauber will collect spiders to stock the nursery cells. One egg is laid in each chamber and will feed upon the fresh caterpillars or spiders upon hatching. When the larva has grown sufficiently it will pupate and metamorphose into a wasp, then chew its way to daylight and leave the nest. The life cycle is complete and will start all over again.

A mud-dauber wasp backs into the chamber with the final spider upon which a single egg is laid

Industrious little creatures arn't they? As with bees, some people might be sensitive to wasp venom, but they are not aggressive, making stinging unlikely. And besides, they are reducing the spider and caterpillar population of your garden - a natural insect control!


Esperance Blog said...

Hi Gaye, a very interesting post. I always wonder where they get the clay from! I am on deep sand, so none close-by meaning my potter-wasps need to travel over 100 metres to a heavier soil. Gos to show how hard these wasps work to collect the mud and their need of nectar. Do yours have to go far?


Gaye from the Hunter said...

Thanks for your interest Jack. I am on black clay soil and with the lack of water this summer there are plenty of ungrassed areas in my yard for the wasps to dig.

I watched the orange potter wasp collect water from the dish I provide in my herb garden which is in the middle of my back yard, then dig in a rock-hard exposed patch of dirt under the clothes line. Then it flew under the back porch awning to construct it's nest on the outside of a cement mixer. The completed nest is 12cm long X 5cm high X about 6cm wide. It has been finished off to perfection with very smooth rendering. That is a mountain of work for an insect!

The wasp dug the dirt and then moistened it with the collected water, so I am presuming it regurgitates the water. I watered the patch it was digging from, but it continued to dig from the dry outer rim of the hardened dirt.

My gardens contain sandy soil, compost and mulch, so not much good for nest building.

The mud-dauber wasp on the other hand, took advantage of the mud I created. The mud-dauber has several 'finishing' techniques for rendering, from lumpy to semi-smooth to a rough maze of ridges.


Anonymous said...

I am learning so much about insects and nature here Gaye. Sometimes when we learn about an insect and see it up close we can value it more. You are shining a light on a hidden world to most.

Gaye from the Hunter said...

Hello MsOcean. Thank you for your comment and I am mightily pleased that you are learning from and enjoying my nature observations, be it from half a world away.

The object of my blog is just what you have observed, ie: learn about and value the nature that we live amongst.

Thank you for taking the time to let me know this, as it is difficult to have any idea how this blog is being received, or even if it is being read, if readers don't make a comment.


Woollybutt said...

Well done once again Gaye, your photos look terrific.

A couple of years ago I moved some books on a bookshelf in our shed and dislodged a nest of a mud-dauber. It was full of leaf-curling spiders and I wonder how the wasp catches them since they are protected by the leaf, perhaps the wasps chew through the leaf? I put the part of the nest that was still intact back onto the bookshelf and the next day the wasps were back and adding more chambers. Fascinating creatures and as you say, they are harmless if you leave them alone.


Gaye from the Hunter said...

hi Peter, I don't have leaf curling spiders here, probably because I don't have suitable leaves (all natives). When I lived in town with exotic plants overhanging the fence, leaf curling spiders were common.

I would imagine that the wasp simply pushes the spider out from the top or backs in from the bottom because I wouldn't think the spider would be a threat to the wasp. But this is just a guess.

The mud-dauber's nest on the brickwork that I have here was partly washed away in a summer storm as it was built too low on the wall (and wasps did not emerge from remaining chambers). Perhaps it was a first attempt and she got it wrong. I have been trying to find out if they nest for more than one season, but as yet haven't found reliable information.

I enjoy your encounters with the creatures that I have been observing. Thank you for sharing them.


Jared Haschek said...

Hi Gaye, great post about orange potter wasps.

I'm working on our balcony today here in Melbourne because it's great weather (yes, great weather in Melbourne, who would have thought) and watching an orange potter wasp make a nest on the wall of our house.

I wasn't sure what to do about it because it looked a little nasty and we have little kids, but after reading your site, I think we'll leave to it it's own devices for a while and see how it goes. Do you know how long the cycle is from the time it makes its nest to when the babies hatch? We don't mind having it there...but we don't really want it there forever. Also, how big is it likely to get? At the moment it seems to be in the process of building its fifth chamber.



Gaye from the Hunter said...

hi Jared,

I am pleased my nature observations could help you with your backyard identifications and queries.

The young should emerge from the nest in about 3 or 4 weeks. Once you see small holes in the nest indicating that the wasps have left, it is then safe to knock the dried mud off the wall with a shovel or similar.

The orange potter-wasp nests that I had here were about 8cm by 5 or 6 cms. The nests of the mud-dauber wasps have been considerably smaller though.

My 3yo grand-daughter was extremely interested in a mud-dauber wasp building on the wall on the back of our house. I let her stand on a chair and get a good view of the proceedure, as I had ascertained that it was safe. We both stood very still on the chair, and once the wasp was satisfied that we posed no threat, it carried on with its building and filling the nest with spiders, undeterred by our close presence. I am not saying that I recommend this, but it was a safe and very educational experience for the child at the time. When these two species of wasp are involved in nest-building, they appear to be consumed with the work at hand. I have never encountered an aggressive mud or potter wasp.

Thank you for your questions, as the added information is sure to assist others who find my site.


Anonymous said...

I have one trying to build a nest in my Printer at work.

Gaye from the Hunter said...

Ah, yes, they do tend to commandeer all manner of our gear and gadgets and clog them up with their nursery chambers. Catching them in the act is the best way to deal with these take-overs, and hope they get the message quickly.

Good luck with it, and thanks for leaving a comment. It's interesting to know the lengths they will go to find a suitable site.


Sarah Fuller said...

Just wanted to say thank you for this great post. I have been watching an orange potter wasp building her nests in my outdoor laundry, which I now make a point of leaving open so she has full access. Today as I was sorting the washing and watching her busying about I noticed that she kept popping under the counter, where it turns out she has another nest. She just kept flitting back and forth between the two, completely oblivious as you said, to what I was doing.

I'm trying to get a good photo of her so I can show her to my blog readers, she is just so pretty and a real joy to watch, but she doesn't seem too happy when I get too close. I don't think she is being aggressive, but she buzzes towards me as if she is checking me out. Is it likely she will sting if I persist?

Well, thanks again for your post. It took me a while to figure out what kind of a wasp she was....and one more thing. The original nest was built last year, is it the same wasp returning or has another one moved in?



ViDa Gonzalez said...

My chain sow wouldn’t start. Two trips to the motor mechanic in town didn’t do much good. And then, an old fellow said, check the air filter, it could be blocked, wasps tend to do that. He was right, somehow, the circular whole in front of the sow was good enough as a nursery and the machine would.’ go.