Orb weaver spiders are widespread arachnids of the family Araneidae, with many species found globally. They inhabit nearly every continent, thriving in diverse environments from forests to urban gardens, excluding the Arctic and Antarctic. Their presence is revealed by intricate, circular webs.
Identifying Orb Weavers
Orb weavers vary in appearance but share common physical characteristics. Many have a stout body with a large, often bulging or triangular abdomen, sometimes with humps or spines. Their eight legs are hairy or spiny, with three claws to navigate non-sticky web sections.
They possess eight eyes, usually in two rows of four, but their eyesight is poor. Prey detection relies on web vibrations, not vision. Mature orb weavers are 1.5 to 3 centimeters long, with females often larger. Coloration varies widely, from reddish-browns and grays to vibrant yellows and oranges, sometimes with distinct patterns or stripes.
The Art of Web Building
Orb weaver spiders are defined by their classic circular, or “orb,” web. They initiate construction by releasing a silk line that drifts until it attaches to another surface, forming a bridge. From this line, a “Y” shaped foundation is established, anchoring numerous radial spokes of non-sticky silk.
After the radial framework, the spider spins a temporary, non-sticky spiral from the center outwards. This guides the final, sticky capture spiral, laid from the outside inward. Orb weavers use strong silk for frame and anchor lines, and sticky droplets on the capture spiral to ensnare prey.
Once an insect is entangled, the spider senses vibrations, bites to paralyze it with venom, and wraps it in silk for consumption. Many species dismantle and consume old webs daily, rebuilding fresh ones each night. Some incorporate a zig-zag silk pattern, a stabilimentum, into webs, which may attract prey or camouflage the spider.
Habitat, Diet, and Life Cycle
Orb weaver spiders are adaptable, found in habitats allowing large web construction and food access. They reside in gardens, fields, and forests, often stringing webs between trees, shrubs, or other structures. Webs are frequently seen near outdoor lights, attracting flying insects and providing a consistent food source.
Orb weaver diets primarily consist of small flying insects like flies, moths, beetles, wasps, and mosquitoes, trapped in sticky webs. Larger species can capture small frogs or even hummingbirds. Juvenile orb weavers, when insect prey is scarce in spring, can consume pollen and fungus spores caught in webs, prolonging their lifespan. Orb weavers generally have an annual life cycle; males are smaller and seek females for mating. After mating, females produce one or more egg sacs, each with hundreds of eggs, before adults die off with colder weather.
Are Orb Weavers Dangerous?
Despite their size and noticeable webs, orb weaver spiders are not dangerous to humans. They are non-aggressive, preferring to avoid confrontation by fleeing or dropping from their web when disturbed. A bite usually occurs only if the spider feels threatened or is trapped, such as when pressed against skin.
Orb weaver venom primarily incapacitates insect prey and is not medically significant to humans. A bite is often compared to a mild bee or wasp sting, resulting in localized symptoms like slight pain, redness, and swelling. These symptoms are short-lived and resolve without medical intervention. While rare, some individuals might experience an allergic reaction, leading to symptoms like nausea or dizziness, in which case medical attention is advisable.