DG's Garden Spiders, Episode 3: contains more Orby, touches on garden ants, introduces another type of spider, cameos various bugs, and features the same dodgy camera work and idle speculation from too little evidence you've come to know and expect from this series.
When we last left Orby she had caught and wrapped a bee in broad daylight which was then left to die from a poisonous bite. The next day dawned with the bee no longer evident in the web. Orby usually leaves the drained bugs hanging, and there has been research done by scientists which indicates that this may be a strategy to entice yet more insects into the web as they may be attracted by the husks. The bee was much larger than the myriad midge and gnat-like bugs that she usually catches so I think it was cut free to ensure web integrity. But spiders don't eat such large prey whole and neither could it simply disappear so quickly. An investigation below the web ensued.
I found the bee in two pieces and you can also see one of the ants involved in consuming its remains. This was something of an epiphany because I've always known that there was a population of ants living in the raised rectangular garden bed where Orby's cactus grows. But it's a desolate landscape and I'd wondered what sustained them. Elsewhere in my yard they can be found feeding on nectar and even the powdery coating on new succulent growth which they gather up into little white mounds and then consume, like so:
But flowers in the cactus patch grow sporadically and linger briefly. They bloom large but I've never found ants feeding on the nectar within and neither are there any powder-coated succulents close by. So what supports their population, I wondered. The dead bee clued me into what perhaps should have been obvious given where the ants have made their nest.
They are not easily seen because they prefer to move beneath the layer of pebbles atop the soil. They have made their base more or less below the spiders web which allows easy harvest of the mana falling from heaven each night. Rarely are they lucky enough to be gifted something as large as a bee. More often it's midges and gnats like these:
But it's enough for ants in this little patch who are, I suspect, more carnivorous by necessity than elsewhere in my yard. It seems to me that Orby is directly supporting the colony. Pretty neat.
Back to Orby and why she does the things she does. Over several days I noticed prey caught in daylight to which she reacted differently. Another bee hit her web, interestingly in much the same top right area as before. If we accept that a sample size of two is enough to base theories on, which it isn't, then perhaps bees instinctively follow the same line of flight when maneuvering through the same obstacles. Orby had again tied and wrapped this bee eventhough it was on the farside of the web from where she hides during the day. I didn't witness it in action.
Another time I noticed a largish housefly that had become entagled. It struck lower on the web and much closer to where Orby rests.
It was well alive and struggling gamely. I have no doubt that Orby was aware of it stuck in the web but she didn't stir. The fly struggled and fought, sending vibrations down the web and many minutes later it finally extricated itself and buzzed off unharmed.
And yet another time I found a despairing bug lying upon a cactus where it had landed after falling from the web.
Only one wing still moved, the other broken in the escape. Now all that remained was to await the ants instead of the spider. The spider would probably have been the quicker death.
All that leads me to conclude that Orby only wraps and bites bees during the day because their struggles are a clear and present danger to her web. I don't think she makes special effort to secure them as food as she's demonstrably content to let a large housefly struggle and eventually escape. The broken winged midge also suggests that small and weak prey are left unmolested, free to manage an escape without spider interference, at least until night falls. I think she captures enough prey to comfortably ignore bees as a food source, but she is unwilling to let them destroy her web investment, and thus they must be swiftly incapacitated whenever they become entangled. Sounds plausible to me, anyway.
Now on to a different type of spider. I don't usually go looking for them, but because of this thread I decided I would do just that. My favourite type of spider in my backyard is the little jumping spider. Also the most commonly found because they are active during the day. They are tiny, harmless and cute. I often see them stalking around but have never been lucky enough to witness one catch anything. Or even try to catch something. But they are still fun to watch so I decided to attempt a few shots. Obviously they knew my intent because I couldn't find a single one. The thing is, when you're looking for spiders you end up finding other things, too.
Such as charming electric blue damselflys shorter than a little finger.
Imposing dragonflys as long as a hand.
Unknown beetles.
And even crickets sunning themselves on pavers in bright sunshine as if wilfully antagonising resident birds.
I gave up as a joke the hunt for the diurnal jumping spider when I instead somehow managed to find a nocturnal creature in full sun. But I didn't abandon the quest permanently and when I tried again a few days later the spiders decided to stop messing with me. The first one I found was a tiny baby, prooving that I don't yet need to update my glasses prescription. The tricky thing about jumping spiders is that they have good eyesight themselves and are quite clever, so they can see you coming and they know when you are studying them closely. Luckily, the very small ones don't seem to care so I was able to get my finger in close enough to attempt an indication of scale.
That's the tip of my index finger, not my big toe. After that I found adults all over the place. Here's another finger shot, this time difficultly achieved because adults are more skittish. Being larger they are more likely to be noticed by predators and so they need be more wary.
Here's a selection of the rest I shot within a quarter of an hour.
The most common species appears to be the one in the first pic at the top. I believe that's the same species as in 2nd, 3rd and 5th shot. The 4th shot is somewhat rarer but the last black jumping spider is the rarest of all. Possibly only because it's the largest and thus the most skittish and difficult to see, so I was pretty happy to manage a photo from a couple of metres away before it disappeared. These charismatic little spiders only use webs to make safety lines before jumping but eventhough they don't make webs I still think they stay within a relatively small home range. I can usually find that spider playing peekaboo in the same green leaved little bush on most days, for instance, as well as the one that lives on the window in the pic above it.
Now back to Orby, a few days after my jumping spider roundup I noticed that her web was fuller than usual with bugs and that she was missing from her cactus post. This was very unusual but I quickly found her on the white cactus sitting in an exposed place where she had never stayed before. I couldn't imagine why. Had she grown so large that she no longer feared bird predation? It seemed unlikely.
So why was she sitting blithely in full sun? On the other cactus where she usually rested both she and Spiny stuck to the shady side at all times. So this was very strange behavior. I watched her for a while but she did nothing and I eventually left her alone. The next day the web was rife with more midges than I had ever seen caught within it and I had an explanation.
Orby was dead. She had moved out of her home and waited to die. The ants were gathering as I watched, celebrating the biggest windfall they had yet received from the web, unknowing that it spelled their doom.
I hope you enjoyed the finale of the three part series "DG's Garden Spiders".
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Topic: Spiders? Spiders. (Read 13792 times)