The European spider of the year 2010 – the garden spider
Araneus diadematus Clerck, 1758

It is one of the best known of all the spiders: the garden spider. Evidence of this is reflected in the number of hits in the search engine ‘Google’. For www.google.at, as of 14.11.2009, there were 166,000 hits for the German name ‘Gartenkreuzspinne’ and 57,100 for the scientific name Araneus diadematus (lat. Araneus = Spider, diadematus = decorated with an ornamental headband or diadem).

Garden spiders belong to the family of orb-weavers (Araneidae). This has around 3,000 species worldwide, about 50 of which occur in Central Europe. These include moderately large to large species (females 10–18 mm, males 5–9 mm) with strongly-spined legs. The spiders generally do not wander, but build a typical orb-web with a sticky spiral capture thread. Other examples of the family include the four spot orb weaver (Araneus quadratus), the marbled orb-weaver (Araneus marmoreus) and the bridge spider (Larinioides sclopetarius).

The garden spider itself bears a characteristic cross shape on its abdomen, which leads to an alternative common name of ‘cross spider’. This distinctive pattern is formed from five white flecks (four elongate, one rounded in the middle) – sometimes merging into one another – and results from an excretory product called guanine being stored directly under the skin in this regions.
The abdomen typically shows a number of leaf-like markings. The abdomen is widest in the first third of its length, which means that the front part looks rather angular, whereas in similar species such as A. quadratus or A. mamoreus the widest point is in the middle and makes the abdomen appear more rounded at the front.
Colouration is highly variable, ranging from yellow to reddish through to various brown tones. Males reach a body length of 5–10 mm, females 12–17 mm.

The garden spider usually builds its large, round orb-web close to the ground or in the lower branches of trees and shrubs. Unlike other Araneus species, A. diadematus normally spends the day in the hub of its web. A retreat close to the web is generally not present, although it can occasionally occur.

Orb-webs are the best known type of spider web, whereby a small amount of silk can form a large capture area. Such a web requires only a few points of contact and yet is secure and flexible at the same time. Signals from an insect struggling in the web are transmitted to the hub at the centre (or to the retreat, depending on where the spider is waiting). Thanks to the special (geometric) arrangement of the web the spider can orientate itself and move about without coming into contact with its own capture threads. The web is regularly renewed, in that the spider simply eats the old web and recycles the valuable ‘building blocks’ (proteins).

A further type of silk is used to construct the egg sacs, which function to protect the offspring. In September and October the female creates numerous egg sacs from yellow coloured woolly silk. The young spiders leave the egg sac after overwintering there and mature into adults by late summer. This species can typically live for up to two years.

The garden spider occupies numerous and various habitats, from forest margins and meadows through to our gardens. Thus it should not be difficult during a pleasant stroll to encounter, and admire, their webs – which are truly a masterwork of nature. Remember how many irritating flies, mosquitoes and other insects this web protects us from, and regard both the garden spider in particular, but also spiders in general, as useful, helpful creatures.

Contact
Austria / Germany:
Mag. Christoph Hörweg, Naturhistorisches Museum Wien, 3. Zoologische Abteilung, Burgring 7, A-1010 Wien, Österreich
E-Mail: christoph.hoerweg (at) nhm-wien.ac.at
Europe:
Dr. Milan Řezáč, Department of Zoology, Charles University, Vinicna 7, 128 44 Praha 2, Czech Republic, eMail: rezac (at) vurv.cz

Countries involved (78 jury members from 21 countries):
Austria, Belgium, Bulgaria, Czech Republic, Denmark, Finland, France, Germany, Great Britain, Hungary, Ireland, Italy, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland.

Bellmann H. (2006):
Kosmos-Atlas Spinnentiere Europas.– 3. Auflage, Stuttgart, Kosmos, 304pp.

Blick T., Bosmans R., Buchar J., Gajdoš P., Hänggi A., van Helsdingen P., Ružicka V., Starega W. & Thaler K. (2004):
Checkliste der Spinnen Mitteleuropas. Checklist of the spiders of Central Europe. (Arachnida: Araneae). Version 1. Dezember 2004. – Internet: http://www.arages.de/checklist.html#2004_Araneae

Foelix R.F. (1992):
Biologie der Spinnen. – 2. Auflage, Georg Thieme Verlag, Stuttgart, 331pp.

Hänggi A., Stockli E. & Nentwig W. (1995):
Lebensraume mitteleuropäischer Spinnen. Charakterisierung der Lebensräume der häufigsten Spinnenarten Mitteleuropas und der mit diesen vergesellschafteten Arten. Miscellanea Faunistica Helvetiae, 4: 459pp.

Heimer S. & Nentwig W. (1991):
Spinnen Mitteleuropas. – Verlag Paul Parey, Berlin, Hamburg, 543pp.

Reichholf J.H. & Steinbach G. (1992):
Die grosse Enzyklopädie der Insekten, Spinnen- und Krebstiere. Band 1. – Bertelsmann Lexikon Verlag, München: 360pp.

Sauer F. & Wunderlich J. (1991):
Die schönsten Spinnen Europas. Fauna-Verlag, Karlsfeld, 4. Auflage, 202pp.

Steiner E. (2007):
Spinnen – Leben am seidenen Faden. – Niederösterreichisches Landesmuseum, St. Pölten, Broschüre zur gleichnamigen Sonderausstellung, 82pp.

The European spider of the year 2010 – the garden spider Araneus diadematus Clerck, 1758

The European spider of the year 2010 – the garden spider
Araneus diadematus Clerck, 1758