Orb weaver spiders are arachnids known for the distinctive, circular webs they construct. These intricate, wheel-shaped webs are a common sight in gardens, fields, and forests. Found globally, thousands of species adapt to various habitats. Their presence is often most noticeable in late summer and autumn when their webs and bodies reach their largest size.
Lifespan and Its Variations
The lifespan of most orb weaver spiders is relatively short, typically about 12 months. This annual cycle means adults emerge in spring, mature over summer, and complete their lives by late autumn or early winter. While a year is common, specific species can exhibit variations; for instance, some furrow orbweavers have been observed to live up to two years, capable of surviving freezing winter temperatures.
A difference in lifespan exists between male and female orb weavers. Females generally live longer than males, often surviving until they lay their egg sacs. Males commonly have a shorter adult life, frequently dying shortly after mating. In some species, this post-mating death in males is a programmed biological event, occurring even without female aggression.
Factors Influencing Lifespan
Several factors influence orb weaver lifespans. Environmental conditions, such as temperature and climate, play a role. Most adult orb weavers do not survive the colder temperatures of late autumn and winter, with many succumbing to the first hard frost. The availability of food, primarily flying insects caught in their webs, directly impacts their ability to grow, reproduce, and survive.
Predation also influences an orb weaver’s survival. Birds, such as honeyeaters, are common predators. Various species of wasps also pose threats; some wasps paralyze spiders to serve as live food for their young, while others parasitize the spiders or their egg sacs.
Life Cycle of an Orb Weaver
The cycle begins in late summer or autumn when the female spider produces one or more egg sacs. These sacs, made of silk, can contain hundreds of eggs and are often hidden in protected locations, such as within curled leaves or dense vegetation, where they overwinter.
In the spring, as temperatures rise, the tiny spiderlings hatch from the egg sac. They may remain clustered for a few days before dispersing. Many spiderlings employ a method called “ballooning,” where they release a strand of silk into the wind, allowing them to be carried to new locations. As they grow, spiderlings undergo several molting stages, shedding their exoskeletons, reaching adulthood during summer. Once mature, adult orb weavers focus on mating and, for females, laying the next generation of eggs before their life cycle concludes.