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St Andrew's Cross Spider - Argiope Keyserlingi (former Argiope aetherea)


This page contains pictures and information about St Andrew's Cross Spiders that we found in the Brisbane area, Queensland, Australia.
Leg to leg female 50mm
St Andrew's Cross spiders are common in Brisbane bushes, backyard and gardens. They are easily recognized by the bright pattern on their body and the cross stabilimentum on their web. St Andrew's Cross spiders build vertical orb web. In the middle they put four thickened zigzag strips in the shape of a cross of 'X'. The spider then hangs head down with its legs pairs together over the cross of 'X'. This is why they are called St Andrew's cross spiders. Adult females build web about one meter in diameters and 1-2 meters above ground. The spiders are active during day and night.


Female St Andrew's Cross spiders are very different from the males. Adult females grow to 15mm in body length. The abdomen is flat oval shaped with transverse white, yellow and reddish-brown stripes. The thorax and head are brownish-silver under sun light. 
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Legs are paired together, brown in colour with yellow bands. 
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On the bottom side of the abdomen there are the yellow lines around the black patterns, with the spinnerets in reddish brown colour. 


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Leg to leg 15mm, adult male                                  Male approaching a female                                  Male and female  
Adult male St Andrew's Cross spiders are much smaller than the adult female. They are dull brown in colour and with no pattern on the abdomen. Both female and male St Andrew's Cross spiders have the hairy silver thorax and banded legs. All St Andrew's Cross spiders, including male, young and matured female, rest with legs in pairs.
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Male with only four legs                                         
We occasionally found male St Andrew's Cross spider with some legs missing. The male in the above picture had only four legs. He could had just mated with a female. In the spider's world, it is common that the female may attack the male. Although this male was lucky enough to escape after approaching a female, half of its limbs were broken.
When the males approach the females, they always stay on the opposite face of the web and slip between the threads for the purpose of mating.

The Stabilimentum

St Andrew's Cross spider and some other spiders make this zigzag band known as stabilimentum. 
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The function of those stabilimentum is uncertain yet. Some believed that the zigzag is used as the sign to warn-off the larger animals. Some believed that it is to stabilize the web. Some suggested that it acts as a sunshade. Some suggested a molting platform and other suggested they are depository of surplus silk. Recently found that those ribbon silk reflect ultra violet light which is attractive to flying insects. This is a typical type of question in Evolution, it may never have a single proven answer. However, usually more than a single answer, or even most answers are correct.
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The female lays her eggs in a silk sac which is close to her web, then she extracts the liquid that dyes the egg-sac into dark green colour.
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Female makes her egg-sac on late summer to early winter. Usually a female makes three or more egg-sacs.


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From late winter to early spring, the young St Andrew's Cross Spiders hatch from the egg-sac. The young spiders stay together outside the egg sac for a few days. Then they climb to the highest point and 'gone with the wind' using the ballooning technique.
Ballooning - A way that many species of spider used for travelling, especially the young spiders. They hold a short length of silk which blowed by the wind current. If the wind is strong enough, the young spiders travel with the wind. By this way spiders can distribute in a very large distrance.

Young Spiders   

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Leg to leg 15mm, young female                              
Female St Andrew's Cross spiders are easily recognised by theirs yellow bands on its flattened abdomen with reddish-brown and white dots. The patterns may be a little different for different individual. The young female spiders are smaller in size, with same abdomen pattern although the colours are paler than the adult female.
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From spring to mid summer, young spiders build web with circular stabilimentum on lower plants. Their orb web is about 30cm in diameter with circular stabilimentum, which make the web centre and the spider highly visible. They are young St Andrew's Cross Spiders. They are pale brown to creamy white in colour. As the spider grows the circular shape is gradually transformed into cross shape. 
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Leg to leg 20mm, elder young female
Sometimes, the St Andrew's Cross spider makes only one line.  Sometimes, not very often, the spider make two crosses. 

Bottom Side

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A closer look at the silk spinnerets of St Andrew's Cross spider. Sometimes the spider build really big cross. When disturbed, the spider will either temporary drop to the ground (bungee jump with safety line) from the web or shaking its web vigorously.
Some orb web spiders, such as the Garden Orb Web Spiders, only set up their web at night. The St Andrew's Cross spiders set up their web 24 hours standby. However, they usually rebuild their web at mid-night if necessary. In day time St Andrew's Cross spiders usually repair (at minimum level) their webs if it was damaged. 
We discussed about how spiders use their silk in this page

On bird's diet menu 

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Photo thank to Trevor Jinks, Gold Coast
The bird is feeding a St Andrew's Cross spider to its young.

1. Wildlife of Greater Brisbane - Queensland Museum 1995, p35.
2. St. Andrews Cross - The Find-a-spider Guide for Australian Spiders, University of Southern Queensland, 2007.
3. A Guide to Australian Spiders - Densey Clyne, Melbourne, Nelson 1969, p67 (Argiope aetherea).
4. Saint Andrew's Cross Spider - Spider Fact sheets, Australian Museum, 2003.
5. Australian Spiders in colour - Ramon Mascord, Reed Books Pty Ltd, 1970, p76 (Argiope aetherea).

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Last updated: November 05, 2009.