a rather confusing story

Part of the fascination of studying nature is that things are often not as simple and uncomplicated as they appear. This is one of those stories that starts off seeming to be one thing, but ends up being something quite else. Let me take you back to the beginning.

There’s an old plastic lawnchair sitting out in the small apple orchard on the far side of the oldfield pasture. We put it there in case anyone ever wanted to take a break. However, it has sat somewhat unused for a number of years. I say “unused”, but that’s not entirely true. It’s adorned by several patches of lichen, and insects make use of it each summer as a place to fasten cocoons.

On May 25th, while making one of my two or three times daily insect walks around the farm, I noticed a female Bronze Jumping Spider (Eris militaris) peering out from between the back slats on the old chair. I photographed her and made a mental note to check back to see if she was still there next time I passed by. My intention was to collect a few observations so that I could submit the data to Spider WebWatch as Eris militaris is one of the species being tracked. The following afternoon, I stopped at the chair to see what was happening. This time, I found a male E. militaris wandering around the edge of the chair back. I shot a few photos of him and moved on. I decided to keep watching the chair to see what would happen next.

I missed visiting the chair for a couple of days as we were busy, it rained for a day, and I was away on Monday doing a nature field day with high school students. I didn’t get a chance to check the chair again until May 29th. This time, I found the male Eris hiding inside a silky refuge under the sheltering curved lip of the chair back (see top photo – click on all photos for a larger view). As I moved in closer to take a couple of photos, the spider moved to a little opening in the refuge. I shot a photo of him gazing out at me (see above).

What I failed to notice – partly due to the small size of these spiders, and no doubt due to my increasing need to wear reading glasses for studying very tiny objects – was that there was another spider a short distance from the male, partly concealed by some objects surrounded by the spider silk. One of these objects — the thing that looks like a bundle of sticks — seems to be the cocoon structure of a kind of moth or other creature that pupates. There are quite a few more of these “stick” structures on the underside of the chair. I didn’t download my camera that evening as I was feeling a little too weary to bother, so I didn’t discover the second spider immediately.

Yesterday (May 30th), while on my morning walk, I turned the chair over to check on the spider refuge. This time, I found a single spider upside down in the refuge (see above). Thinking that it was the male spider (still not realizing that there had been *two* spiders in the refuge when I photographed it on May 29th), I gave the silk a little tweak to see if the spider was alive. It began to move, and flipped upright so that I could see that it was a female Eris militaris — females are marked quite differently than the males. I checked the rest of the chair and the male was now nowhere to be found. Unfortunately, while moving the chair, the female decided to rappel off into the vegetation below the chair. I set the chair back in place as carefully as possible and went on my way — a little annoyed at myself for having disturbed the female spider.

Last night, I decided to revisit the chair in the orchard to see if the female had found her way back to the refuge (this was bothering me greatly). Indeed, she was back on the chair, but now she was inside another refuge located just a few centimeters from the original one (see below). I’d noticed the second refuge on May 29th, but thought that it must be old. Among the things that I find puzzling is what those strange oval objects might be. They seem to be encrusted with tiny bits of debris which, based on my photos, look as though they might consist of insect parts. I’ll have to take a closer look at one with my 15x loupe next time I visit the spider chair. Also, I’m wondering if the black, barrel-shaped object in the third photo down might be a spider egg case. I did some searching around for photos of Eris militaris egg cases, but came up empty-handed. Perhaps David Shorthouse will find his way over here and be able to offer some expertise.

I’ll continue to watch these spiders and will post some notes to Spider WebWatch sometime soon. What I find particularly interesting is that it seems that the male spider must have been engaged in some form of mate- or nest-guarding behaviour. So far, I haven’t come across references to such a thing, although I know that such behaviour is sometimes seen in other invertebrates such as dragon and damselflies who stick with their mates until eggs are safely laid. As I found another male E. militaris on a nearby bush on May 29th, I suppose there was some threat that a competitor might happen along to disturb this pair.

Anyhow, all of this spider activity is quite interesting to observe. I think we tend to dismiss small creatures as being incapable of complex behaviour when, in fact, there’s quite a lot going on.

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6 Responses to “a rather confusing story”

  1. robin andrea Says:

    The richness of life on the lip of an unused chair absolutely amazes me. Your photos are grand, Bev. Quite a story too.

  2. Cathy Says:

    “To see a world in a grain of sand . . .” or in this case – on the backside of a lawn chair. It’s a little sobering to think how easily I’ve brushed these worlds-writ-small off our stacked lawn chairs.

    On my first read through this little mystery, I was concerned that you’d found that the female had decided to add the male to her larder :0) Whew.

    This is all so neat.

  3. bev Says:

    robin – I’m constantly amazed by what may be observed in the smallest of areas. It’s the point that I like to stress when anyone asks me where to find interesting things.

    Cathy – Yes, I guess that’s the best way to describe it — seeing the world in a grain of sand. I’ve become increasingly conscious of the truth of it. Regarding the female and male jumping spiders — I’ve often seen pairs together and haven’t actually observed the female attack the male as is common in some other spider families. I don’t think jumping spiders have that tendency — perhaps because the males are pretty much the same size as the females, which is not the case with many of the other families where the male is very small.

  4. Xris (Flatbush Gardener) Says:

    I’ve decided I’m going to break down and buy a macro lens as soon as it’s back in stock locally. There’s so much little life around the house here, some of it at the limits of my vision. It’s not only on the plants, it’s in the soil, now that I’ve had two years to build it back.

  5. Larry Ayers Says:

    A macro lens, especially when combined with a two-element diopter, is a wonderful amplification of the visual world. What really inspires me is that photos taken with such a set-up show details when enlarged on the computer screen which I didn’t notice at all at the time the shot was taken.

    Bev, your photos just inspire me; I’ve always been fond of spiders and I need to branch out from my moth photos and try to take some of arachnids.

  6. Jimmy Says:

    So cool…your story reminded me to put my old chair out in my garden.