This female Common Cucumber Spider, Araniella curcurbitina, scuttled away as I gathered up the ivy that I’d cut back from behind the herb bed. I’d spread an old shower curtain on the ground to catch the trimmings, hence the background; the weave of the cloth gives a clue to the scale: the spider is just half a centimetre long, excluding legs.
The cucumber spider is common on trees, woods and hedgerows, where it spins a small orb web. It has a conspicuous red spot on its underside, just below the spinnerets. The male has boxing-glove style pedipalps (the small front pair of legs).
Britain’s Spiders, A Field Guide
Identifying it gave me a chance to use my new field guide, Britain’s Spiders, by Lawrence Bee, Geoff Oxford and Helen Smith (2017).
As I already have two spider field guides on my shelf, Collins Field Guide Spiders of Britain & Northern Europe, by Michael J. Roberts (1995), and The Country Life Guide to Spiders of Britain and Northern Europe by Dick Jones (1983), did I really need another?
Dick Jones had support from Kodak and Pentax when he photographed 350 species of spiders and harvestmen for the Country Life Guide (top right), but his Kodachromes can’t quite match the clarity of the digital photographs in the latest guide, which also has the advantage of up-to-date distribution maps, even so, the Country Life Guide is useful to have for a second opinion when you’re checking out a species.
Collins Field Guide
If you were getting serious about identifying spiders, you’ll need a copy of Michael J Roberts’ guide, because, in addition to 288 colour paintings, he includes 1,500 line drawings of the spiders’ reproductive organs, which would be essential if you were trying, for example, to distinguish between the Common Cucumber Spider, Araniella curcurbitina (which is most likely to be the one that I found), and it’s near identical relative, the Cucumber Spider, A. opisthographa.
“The distinguishing features of the male palpal organs are best seen from below,” says Roberts, “and this is difficult with a field microscope, unless the specimen is particularly obliging.”
He explains how to construct a homemade ‘spi-pot’ to harmlessly examine a spider in the field. But don’t feel inadequate if you can’t tell one species of cucumber spider from another because it seems that even the spiders themselves occasionally get it wrong:
“Very rarely, specimens may appear rather intermediate, possibly due to hybridisation.”