Knobbled Orbweaver

Appearance

"Socca pustulosa" is a perfect example of a symmetry orb-weaving spider, with its intricately glittering orbweb representing the pinnacle of spider evolution. Their abdominal characteristics are the most distinguishing features: roughly triangular shape with two noticeable humps towards the front and five-pointed knobs on the dorsal posterior abdomen. More interestingly, most are covered with a leaf-shaped pattern and various colouration on the abdominal surface, from reddish-brown to yellow or even green, while some have duller colours like greys, whites, or pure black. Mouthpart is another clue to be recognised as Chelicerae, with four teeth on promargin and three on retromaringin, functioning as holding prey when sucking up the fluids from insects.

In general, female spiders tend to be larger than males of the same species, and this is also true for "Socca pustulosa"; the females of "S. pustulosa" are almost twice as large as males, with a body length of about 11 mm, while males are weighing about 6mm. In addition, the precise identification of "S. pustulosa" relied on the reproductive organ, which is the unique trip-partite terminal apophysis amongst the "Socca" genera; the terminal appendix is an elongated, sometimes threadlike apophysis located between two firmly sclerotised basal and apical lobes. In terms of the female genitalia, the epigyne plate appears roughly square-shaped in ventral view and has a broad atrium. The scape, which bears relatively long setae, is elongated and typically extends beyond the posterior margin of the epigyne plate.

Naming

Scientific name: "Socca pustulosa"

Common name: Garden Orb-weaver Spider.

Habitat

"Socca pustulosa" tends to stay in any open vegetation habitat exposed to the sun, occupying a wide range of shrublands, forests, and even gardens. Nevertheless, they rarely penetrate deep into dense native forests. Instead, their prey will determine their habitat preferences and whether have enough structures to help them disperse and support their webs, which is the critical factor to hunt, including tree branches, twigs, weeds, fences, and bushes. In contrast, landscape alteration and fragmentation are caused by anthropogenic effects, deforestation, and urbanisation, which have provided many suitable habitats for them.

Food

Like any other orbweb spider, "Socca pustulosa" uses its typical spider webs to prey on flying insects; small insects like flies, moths, beetles, wasps, and mosquitoes become their primary food source. Nearly all orbweb spiders are nocturnal; therefore, web-constructing usually takes place at night, but sometimes they may also be found spinning their web in the middle of the day if the weather is dull or overcast.

The intricate orbweb is their efficient predation tool, silk is produced by spiders through specialized glands called spinnerets, which are situated at the end of their abdomen. To begin with, females "S. pustolosa" spend some time exploring their surroundings, laying a dragline as they travel back and forth, that not only expands their boundary threads from suspension but also might leave for later web forming. After a strong top bridge line linking two trees or bushes, the next step is to spin several anchor points attached to each side, using one of the loose threads pulled down vertically to form a Y-shape as the central structure, with more silk reinforcing the central hub from which spiral outwards; noticeably that this first radiational orbweb is not sticky but act as a framework. Following the first layer, the spider exchanges silk production into sticky silk form, starting a spiral at the outer edge of the web by crossing between the non-sticky wave that radiates from the centre hub to its edge, more specifically called dry scaffold threads; thus, a new glinting enduring orbweb is ready for the hunt. At this stage, the spiders rest in a head-downwards position and enter into stationary prey mode; when detecting the vibration from any ‘food’ mistakenly enters their territory, they can quickly swing down and prey.

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Predators

While "S. pustulosa" are predominantly predators, other creatures can frequently prey on them. In New Zealand, there are many parasitoid wasps targeting spiders and insects. Unlike parasites, parasitoids ultimately cause the death of their host. For instance, "Pison spinolae," widely recognised as the mason wasp, belong to the solitary member of the Crabronidae family and is distributed across the entire New Zealand region; it commonly prey on orb-weaving spiders. The mason wasps use venom through their stinger to inject into spiders which paralyses them. Then, using their strong legs to drag their prey back to the burrow, the spider is placed in the mud-walled chamber and rendered immobile. The hatched grub eventually consumes the spider alive as nutrients until nothing remains.

Another well-known spider-hunting wasp is the spider wasp; for example, "Priocnemis monachus", the female "P. monachus" hunt during daytime, swiftly stinging their chosen spider prey upon discovery, effectively paralyzing them. The incapacitated spider is subsequently dragged to a burrow and lays an egg on top of the spider's abdomen. Once the egg hatches, a larva emerges and gradually consumes the paralyzed spider while it remains alive until entirely devoured.