Wednesday, 23 July 2014
A bit later, then, in my street, a couple of migrant hawkers were hunting over the verges. Migrant hawkers often hunt together with other individuals, and they may settle to bask near each other. They tend to hunt from 4-5 m above ground. I managed some records shots, this one the best.
Saturday, 19 July 2014
During the first half of June the female may be see trundling along with a huge light-coloured egg sac under her sternum which is attached to her spinnerets by threads and is held in her chelicerae. At about the time the eggs are beginning to hatch, she loosens the outer covering and attaches it to a blade of grass. The she weaves a tent over it on the outside of which she stands on guard [...] The young emerge in late June or early July, after moulting once inside the egg sac. Now they cluster together in a ball inside the tent for a few days before moulting for a second time and dispersing.I found the first nursery with already emerged spiderlings on the 20th of June. Bristowe was of the opinion that Pisaura will have two batches of eggs. Although the female below was carrying an egg sac on the 4th of July, I am not sure if this represents variation on the date of reproduction of different individuals as they mature, or evidence of a second batch.
Female carrying her disproportionate egg sac. They appear to walk on tiptoes holding it. I don't think the female is able to hunt while carrying her egg sac.
This spider has a fresh nursery web and appears to be manipulating the egg sac to allow the spiderlings to emerge.
Unlike the neat, smooth new tents holding clustered spiderlings the tent above has a few holes (made by the female?) allowing spiderlings to disperse. The spiderlings are clustered forming a ball just visible at the top right hand corner of the nursery tent.
The spiderlings are often clustered together in a ball like garden spider ones. The ones above look like they are ready to leave their tent.
If you click to enlarge the photo you might be able to see some tiny spiderlings on top of the tent already leaving.
I haven't found any information as to the function of the nursery web. Certainly it keeps the spiderlings dry during rain, and the mother is often found underneath also during poor weather. It could offer protection from parasites or predators. Many predatory insects will readily take spiderlings, including wasps, and it appears that the nursery web is not totally wasp-proof, as these photos on Flickr show.
Friday, 18 July 2014
Teneral Forest Bug
Large shieldbugs are relatively easy to identify, even at their nymphal stages. The British Bugs site is always good starting point.
Saturday, 12 July 2014
I sat by the edge of the pond, and was entertained by several pond skaters squabbling for a dead mirid bug.
Another smaller individual, also a male, crossed the pond rapidly. In a cursory view they do look remarkably like pond skaters, specially due to the pale fringe of the abdomen and the way they move on the water...
...but he crossed the pond again and I lost it too.
Then I spotted another one. This one looked quite shy and reluctant to move, and it sat hidden by the stems on the water edge.
It then become obvious why the white stripes, these are very similar to the reflections of the water on the edge of the pond, and probably help concealing the spider to their predators, and possibly their victims.
Out of the six British species of Tetragnatha, two are larger and more common and one of them associates with water, T. extensa, although detailed genital examination is needed for a secure identification.
Tetragnatha have very large jaws, and the males using their modified jaws to lock the female's in place - and keep out of danger - when mating.
You can see the folded fangs in this shot
And this is a scanned figure from Bristowe's The World of Spiders (1958), drawn by Arthur Smith, demonstrating the locking mechanism (male at the bottom)
I took this shot to give you an idea of the size of the spider
For a wonderful account of the mating behaviour and natural history of these spiders, go to the Spiderbytes blog.