WOODLAND AND HEDGEROW - SPIDERS




 

 

The episode focusing on Arachnidae (spiders) in Life in the Undergrowth on BBC was one of the best in the series and with luck it might have persuaded a few people that these invertebrates are to be admired rather than feared. A boss in industry would surely relish an employee with the qualities spiders show – they are determined, effective, decisive, productive and not wasteful.

Spiders in woodland and hedgerow would provide a lifetime’s study, so those here represent just a selection to display some of the different families and behaviour.

The Orb-web spider Tetragnatha extensa (body 12mm), from the Tetragnathidae family, builds an inclined web with few radii and spirals in damp places.

Marpissa muscosa (10mm), from the Salticidae family, is a nationally scarce jumping spider, larger than most of that group and found under bark or in crevices in trees or fence posts. A female is shown in the Gardens section of the website.

Pisaura mirabilis (15mm) is a sizeable member of the Pisauridae family and commonly called a wolf spider, using speed and mobility on the ground rather than a web to chase and catch prey. They bask in sunshine regularly.

Uniquely, males present a courtship gift to females, who carry eggs in a sac underneath until they hatch. As the picture above shows, this is quite a commitment, but the females can move almost as fast with the encumbrance as without, and the fact that spiders do not need to hunt every day helps.

This behaviour is also shown with a Pardosa lugubris female (6mm), from the Lycosidae family. After hatching, the spiderlings are carried on the back. There are getting on for 20 Pardosa species in the UK, a number of which are hard to tell apart.

The Agelenidae/Hahniidae family is small and there only two of the Agelenidae genus in Europe. Agelena labyrinthica (11mm) is pretty common and examples of its often large sheet web narrowing into a tunnel where the spider lies in wait are seen in many vegetated areas, usually not far above the ground. This species is a high-speed operator if it senses anything coming on to the web, and it is also very sensitive to human presence, disappearing pronto.

Misumena vatia (10mm) is probably the best known and most often seen member of the Thomisidae family, the so-called Crab Spiders. Females habitually skulk on plants, mostly white like Ox-eye Daisy (Leucanthemum vulgare) but also yellow or green, awaiting prey. They can change colour to match the plant in as little as two days – the second image shows the yellow form – and are capable of using their pincer-like front legs to catch and eat large Hymenoptera such as bumblebees.

On occasions, though, as in the third picture of the species above stalking a male Osmia rufa, they lack the size to complete the circle in the pincer movement and fail. The bee showed no sign of concern after the failed attack and carried on nectaring on the plant.

The Cross or Garden Spider (Araneus diadematus, 12mm) is the most often seen member of the Araneidae family, with its often perfectly circular and beautifully constructed webs seeming to fill almost any habitat when you walk towards the sun on a dewy morning.

The webs can be 40cm in diameter and are found at up to 2.5 metres above the ground. Even social wasps can fall prey to the largest specimens of the species, whose dozens of young hatch in bulk and stay together as a group in the very early stages before dispersal.

Harvestmen are related to spiders and with around 3,500 species worldwide are hardly a small group. Most in the UK are easily distinguished by having long legs as well as the standard design of a single body unit with a turret (ocularium) above this for the eyes.

They lack poison, or silk to construct a trap, but are fast and capable of catching small prey. Equally, they scavenge on almost anything, including bird droppings and even, according to Dick Jones in his excellent out-of-print book on spiders published by Country Life, marmalade. Harvestmen are prone to infestation by mites, as the image shows.

Certain woodland and hedgerow spiders can fall prey to one of the minority of spider-hunting wasps found in this environment more often than heathland, namely Priocnemis perturbator (14mm).

This species is one of a handful, all of them relatively large and also including Priocnemis susterai and Anoplius viaticus, which overwinter as adults and appear in the spring. Priocnemis perturbator, which is reasonably common and has long antennae, can often be seen nectaring on Wood Spurge (Euphorbia amygladoides). Priocnemis susterai is very similar in appearance and size and really can be separated from its relative only by the use of an eyeglass or microscope.

Priocnemis perturbator follows the method of the majority of spider-hunting wasps in hunting out prey, which is paralysed then transported to a burrow where the spider has an egg laid on the abdomen and is interred to provide sustenance for the resulting larva.

Arachnospila spissa (to 12mm), which also inhabits mainly vegetated areas, is one of the largest spider-hunting wasps. Not too difficult to find on the margins of woodland, they have a different approach to the same end of finding food for their offspring, attacking prey in the nest and leaving it there paralysed.

Dipogon subintermedius (10mm) is probably the commonest of the three Dipogon spider-hunting wasps in Britain – Dipogon variegatus is covered in detail in the Heathland section of the website. Subintermedius favours woodland and hedgerow, uses old beetle burrows in wood for its nest and catches exclusively Segestria senoculata, a species often found under bark.

Images © Jeremy Early. All rights reserved.

My latest book, My Side of the Fence – the Natural History of a Surrey Garden, was published in spring 2013. Details may be found, and orders placed, via this hyperlink My Side of the Fence.

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