27-5-2023 TABIN RESERVE, BORNEO - GIANT GOLDEN ORBWEAVER SPIDER (Nephila pilipes)

Nephila pilipes (northern golden orb weaver or giant golden orb weaver) is a species of golden orb-web spider. It resides all over countries in East and Southeast Asia as well as Oceania. It is commonly found in primary and secondary forests and gardens. Females are large and grow to a body size of 30–50 mm (overall size up to 20 cm), with males growing to 5–6 mm. It is the second largest of the orb-weaving spiders apart from the recently discovered Nephila komaci. The first, second, and fourth pairs of legs of juvenile females have dense hairy brushes, but these brushes disappear as the spider matures.

The N. pilipes golden web is vertical with a fine irregular mesh. It is not symmetrical, with the hub usually nearer the top. Rather than egg sacs being hung in the web, a pit is dug which is then covered with plant debris or soil.

Nephila spp. prey upon only a few species. Nephila spp. will remove some specific insects from their webs. They avoid vespid wasps, alate ants, and other insects that secrete distasteful compounds. Due to Nephila’s large body size, it can prey on insects with a broad size range, from 2 mm to even larger size than themselves. They adopt different strategies for different sizes of preys. Small preys are directly caught and removed from the web. For larger ones, they inject venom and wait for the decease of their prey. However, Nephila spp. have a dramatic change in predation style from the spiderling to adulthood. During the spiderling stage, they feed collectively on a common web. Upon reaching adulthood, they construct their own webs. Nephila spp. also reserve food caches to deal with periods of food shortage. They wrap surplus prey in silk and store them in the hub of the web. The silk covering can significantly reduce water loss due to evaporation. Food cache can reduce weight loss during periods with limited preys.

It has been reported that some N. pilipes can adjust the ultraviolet radiation reflected by stripes on their body to attract preys that are UV light oriented. The bands on the legs and body of N. pilipes can reflect UV radiation, so they are more visible to flying insects. The contrast of colors makes them look like food sources for insects, rather than a predator spider.