Citizen Spider Science
In mid-December last year, a St Andrews Cross Spider set up home on the outside of our dining area window.
Spiders on our windows are not unusual, but this caused a bit of a stir as she was relatively large, her big orb web placing her at about kid eye level.
Anyway, I was sick of Ms5 squealing when she saw spiders (very much learned behaviour), so called them over to take a closer look. You don't often get to see the under-side of a spider up close. Both were interested. I didn't really expect her to survive there long.
Front and Back views, Dec 18.
After that she moved to the opposite side of the web, so our closeup views are now at the normal angle.
We watched her web construction, noting when she added a second spoke to her cross, then a third, and finally celebrated the construction of a full cross.
We watched her eating breakfast, and getting gradually bigger and plumper. We admired her coloured patterns.
I was less admiring of the mess she made of the window. I've never given any thought to the question of spider excrement before.
I was a bit worried about her health for a few days in early January when she let her web fall into disrepair and the strands of the cross started going in all directions. It seemed she wasn't bothering to rebuild it each night, but just adding an extra stick or two to the cross construction. At one point we counted 7 of them.
Then one morning, January 7th, her web was perfect again. The second thing I noticed was the egg sac that had appeared near the top of the window, and that our spider looked a lot slimmer again.
I think it was the next day we noticed that she had another spider in the web with her. A much smaller one who we deduced must be a male St Andrews Cross Spider, and assumed he was the dad.
After a few days I had decided they must not be the sort of spiders that eat their mates since he was still there, but that was when I saw her leap at him out of the corner of my eye.
The kids came over to watch as she swiftly wrapped a few strands around him then started to eat.
These spiders only fully wrap large prey. Small ones they just bite, or wrap a few strands around to hold them then chow down.
The following day I noticed a general absence of the other spiders who normally lurk at the edges of the window. I suspect she felt hungry.
Photos: Hi daddy-spider. Bye Daddy spider.
Following her big meals she got plump again, but I was surprised one morning to come down and find a second egg sac in the window. It hadn't occurred to me that a spider would make more than one egg sac in a season. I guess dad-spider was actually dad2. Once more she was a slim spider.
Today was the big day when the baby spiders emerged. I wasn't sure we'd get to see it, night time would seem a more sensible time for spiders to hatch. This morning however the kids called me over with great excitement to see hundreds of tiny spiders emerging on masse (and quite slowly) from the first sac.
So the answer to the question of how long it takes St Andrews Cross Spiders to hatch is apparently around 26 days.
(Strangely, the internet has let me down on finding a detailed life cycle of this particular spider.)
She is looking very plump again. I wonder if there are more babies on the way.
For the moment, we are waiting to see if any of the baby spiders spin a little doily to sit on, which is apparently what they do until they get big enough to do the crosses.
Now that the sun has come out, the babies have huddled together in a big furry ball. I hope they don't get too hot sitting in direct sunlight there...
Mummy and baby spiders today.
She is about 4cm from rear leg tip to front leg tip. The main part of the egg sac is about 2cm.
I've also put up some short videos. In this one you can hear that Ms5 is no longer squealing at the sight of spiders.
https://youtu.be/IxlRWdalegE
Edit: And lo, the following morning there was a 3rd egg sac, and our spider was slim again.
The babies seem to be active at night and in the morning, then huddle together in balls during the afternoon. The numbers seem to be dropping, but the mechanism is not clear.
Spiders on our windows are not unusual, but this caused a bit of a stir as she was relatively large, her big orb web placing her at about kid eye level.
Anyway, I was sick of Ms5 squealing when she saw spiders (very much learned behaviour), so called them over to take a closer look. You don't often get to see the under-side of a spider up close. Both were interested. I didn't really expect her to survive there long.
Front and Back views, Dec 18.
After that she moved to the opposite side of the web, so our closeup views are now at the normal angle.
We watched her web construction, noting when she added a second spoke to her cross, then a third, and finally celebrated the construction of a full cross.
We watched her eating breakfast, and getting gradually bigger and plumper. We admired her coloured patterns.
I was less admiring of the mess she made of the window. I've never given any thought to the question of spider excrement before.
I was a bit worried about her health for a few days in early January when she let her web fall into disrepair and the strands of the cross started going in all directions. It seemed she wasn't bothering to rebuild it each night, but just adding an extra stick or two to the cross construction. At one point we counted 7 of them.
Then one morning, January 7th, her web was perfect again. The second thing I noticed was the egg sac that had appeared near the top of the window, and that our spider looked a lot slimmer again.
I think it was the next day we noticed that she had another spider in the web with her. A much smaller one who we deduced must be a male St Andrews Cross Spider, and assumed he was the dad.
After a few days I had decided they must not be the sort of spiders that eat their mates since he was still there, but that was when I saw her leap at him out of the corner of my eye.
The kids came over to watch as she swiftly wrapped a few strands around him then started to eat.
These spiders only fully wrap large prey. Small ones they just bite, or wrap a few strands around to hold them then chow down.
The following day I noticed a general absence of the other spiders who normally lurk at the edges of the window. I suspect she felt hungry.
Photos: Hi daddy-spider. Bye Daddy spider.
Following her big meals she got plump again, but I was surprised one morning to come down and find a second egg sac in the window. It hadn't occurred to me that a spider would make more than one egg sac in a season. I guess dad-spider was actually dad2. Once more she was a slim spider.
Today was the big day when the baby spiders emerged. I wasn't sure we'd get to see it, night time would seem a more sensible time for spiders to hatch. This morning however the kids called me over with great excitement to see hundreds of tiny spiders emerging on masse (and quite slowly) from the first sac.
So the answer to the question of how long it takes St Andrews Cross Spiders to hatch is apparently around 26 days.
(Strangely, the internet has let me down on finding a detailed life cycle of this particular spider.)
She is looking very plump again. I wonder if there are more babies on the way.
For the moment, we are waiting to see if any of the baby spiders spin a little doily to sit on, which is apparently what they do until they get big enough to do the crosses.
Now that the sun has come out, the babies have huddled together in a big furry ball. I hope they don't get too hot sitting in direct sunlight there...
Mummy and baby spiders today.
She is about 4cm from rear leg tip to front leg tip. The main part of the egg sac is about 2cm.
I've also put up some short videos. In this one you can hear that Ms5 is no longer squealing at the sight of spiders.
https://youtu.be/IxlRWdalegE
Edit: And lo, the following morning there was a 3rd egg sac, and our spider was slim again.
The babies seem to be active at night and in the morning, then huddle together in balls during the afternoon. The numbers seem to be dropping, but the mechanism is not clear.