Foliage Webbing Spider
The foliage webbing spider is a widespread species. It is found in open forest, woodland and shrubland throughout much of mainland Australia. A closely related, non-communal species (Van Diemen's webbing spider, Phryganoporus vandiemeni) is found in Tasmania. (VIC, SA, WA, NT, QLD, NSW).
These spiders are 6 to 10 mm in body length, silvery grey to brown in colour and have with a contrasting pattern of light and dark brown markings on the abdomen. The young spiders delay their dispersal and live together in groups in a communal nests built on plant foliage until they reaching the subadult stage. The genus is related to the black house spiders (Badumna spp).These nests are built on plant foliage.
Ecology/Way of Life:
Foliage webbing spiders are unusual in having a periodic-social life-cycle, that is, one that includes a period when the spiders live together socially, followed by a period when they live alone. Throughout summer, spiders leave their communal nests to take up solitary lives. The females leave first, as subadults, whereas the males leave somewhat later, mostly as adults. As a result, mating between male and female spiders from the same nest is unlikely, which promotes a greater exchange of genes in the population.
Each solitary female builds a small, irregular, sheet web with sac-like retreat tubes on the foliage of shrubs (often spiky species) and in small trees such as mallee eucalypts. After mating, she produces up to 16 lens-shaped egg sacs over several months, each containing between 100 and 3900 eggs. Importantly, once spiderlings emerge from the egg sacs, their dispersal is delayed, and so they stay together as a colony until the following summer. By then, the spiders have reached the subadult stage and begin to disperse from the nest.
The communal nest consists of an inner retreat area, with numerous entrances holes opening into a network of inter-connecting passages, and an outer area made up of ladder-like layers of cribellate silk, where prey is captured. The nests vary greatly in size and number of occupants. The nests of a population studied intensively in Queensland population housed from 9 to 224 spiders. One football-sized nest from the Victorian mallee region contained 661 spiders (558 juveniles spiders, 40 males and 23 females). Larger nests attract a wide range of arthropod parasites, predators and scavengers. Some of these may attack the eggs and young of the host spider's eggs and young, reducing the size of some colonies or causing some to fail.
Social interaction is most highly developed between juvenile spiders and less so between subadults and adults, which are those in the process of dispersing. Juveniles will cluster together and undertake collective tasks such as nest construction and cleaning, capture of food, and feeding. However, these juveniles may behave cooperatively because they are giving out pheromones which promote tolerance and cooperation. Such behaviour is different from the truly cooperative behaviour shown by spiders and insects that are permanently social.
Interaction with Humans/Threats:
In past years, orchardists in south-eastern Australia complained of foliage matting, leaf fall and limb damage caused by infestations of foliage webbing spiders. Orchard pests such as thrips can shelter within the nests where they are protected from pesticide sprays. Graziers in western New South Wales occasionally complain that shrubby native fodder plants become unpalatable for cattle or sheep because they are festooned with the silk nests. In such situations, spiders can also be useful biological control agents, capturing pest insects.
The species was named by L. Koch in 1872; the genus name is based on the Greek: phryganon = dry stick and poros = a hole or passage; referring to the web, often built on dry, sticky shrubs and with a definite entrance; the species name comes from the Latin: candidus = shining white, referring to the colour of the body.
Downes, M.F. (1993). The life history of Badumna candida (Araneae, Amaurobioidea). Australian Journal of Zoology 41(5): 441-446.
Downes, M.F. (1994a). Tolerance, interattraction and cooperation in the behaviour of the social spider, Phryganoporus candidus (Araneae, Desidae). Bulletin of the British arachnological Society 9(9): 309-317.
Downes, M.F. (1994b). Nest of the social spider Phryganoporus candidus (Araneae: Desidae): Structure, annual growth cycle and host plant relationships. Australian Journal of Zoology 42(2): 237-260.
Gray, M.R. (2002). The Taxonomy and Distribution of the Spider Genus Phryganoporus Simon (Araneae: Amaurobioidea: Desidae). Records of the Australian Museum 54: 275-292.
Topics:Spider webs Pheromones Social behaviour Silk
Text & map by Mike Gray; photograph by Mike Gray, courtesy of the Australian Museum.
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