Friday, 17 August 2012

Candy-stripe spider

 I found four Candy-stripe spider, Enoplognatha ovata, females guarding their lovely blue egg sacs under the lid of my garden waste bin. The spiders have probably been transferred to the bin with branches cut from some bushes, and had moved with their egg sacs to the drier lid. This one floated down from a thread of silk, and I brought it home to take her portrait on the white bowl. Another thread of silk attached the female to its egg sac, as can be seen on the following side shot:
Although these are small spiders, about half a cm long excluding the legs, they are powerful hunters, and they are able to subdue wasps, honeybees and even the aggressive Wool Carder bees, which they capture on their loose, disorganised web under flowers or leaves, where the females guard their egg sac:
Enoplognatha with its male Wool Carder Bee prey
this one with wasp
with Episyrphus balteatus hoverfly
This one hiding underneath a Feverfew flower got a honeybee
This spider shows a striking color polymorphism, which is genetically determined in a complex way. I have found the three colour forms in my garden. The abdomen can be plain pale yellow (variety lineata, top shot), yellow with two dorsolateral pink stripes (var. redimita):
or yellow with the dorsal surface of the abdomen entirely pink (var. ovata), the rarest in my garden:
In addition to the colour polymorphism the presence and number of black spots is also variable, as it can bee seen in the above photos. This species also occur on both coasts of the USA, presumably introduced from Europe. In the UK, there is a very similar species, also colour polymorphic, E. latimana, which has been recorded mostly in the south of England and it appears to be less common than E. ovata.

1 comment:

Anonymous said...

Are there many worker wasps around in your part of the UK this year? Here in Northamptonshire, as of 18th Aug, I have not seen a single worker wasp anywhere at all this year. I'm not exaggerating - I don't simply mean there are far fewer of them than usual; there are absolutely no wasps at all to be found. (Friends and work colleagues all concur, when I mention it).
Back in late March, during the brief warm spell, I saw several queens buzzing about, and again in late May, I saw perhaps a few more queens than usual. Just once in mid July, a wasp came in through the window at work, and again, I think it was a queen, as its movement was slow and lethargic, not curious and foraging (and judging by its size). Since then, not a peep from the wasp species. I keep thinking "they're just a bit late this year, next week they'll emerge in force", but surely by 18th Aug any viable nests should be up and running.
I'm guessing that the spectacularly wet April/May/June has decimated their food supply, as others have commented upon the scarcity of butterflies this year, so I'm thinking 'no caterpillars = no food for the wasp grubs'.
But still, this is unprecedented, I have never known an August completely free of wasps. I wonder, how often does this occur, is it nationwide or is the story very different in other counties, and how long will it take for their numbers to recover?