Orb weaver spiders are arachnids known for constructing large, circular webs. These predatory spiders play a significant role in various ecosystems by controlling insect populations. Their intricate web designs allow them to effectively capture a wide range of prey.
Main Food Sources
The primary diet of orb weaver spiders consists almost entirely of insects. As generalist predators, they will eat nearly anything caught in their webs. Common prey items include flies, moths, mosquitoes, beetles, wasps, grasshoppers, and cicadas. They primarily target flying or jumping insects that become entangled in their sticky webs.
Beyond insects, some orb weavers, especially juveniles, consume pollen and fungal spores. Studies show that pollen can constitute up to 25% of a juvenile’s diet and increase life expectancy. These spiders actively digest pollen by injecting enzymes, rather than accidentally ingesting it. This suggests that while insects form the bulk of their diet, supplementary nutrients are obtained from plant matter.
How Orb Weavers Catch and Eat
Orb weaver spiders are named for their distinctive, wheel-shaped webs, which serve as primary hunting tools. These webs feature radial strands for structural support and non-sticky pathways, while concentric spirals are coated with a sticky substance to trap prey. When an insect flies into the web, its struggle creates vibrations that alert the spider. The spider, often waiting in the center or a nearby hiding spot with a signal line, senses these vibrations through its legs to pinpoint the prey’s location.
Upon reaching trapped prey, the orb weaver quickly subdues it by biting and injecting venom, which paralyzes or kills the insect. The spider then rapidly wraps the prey in silk, often rotating it to create a secure package. This silk wrapping prevents the prey from escaping and preserves it for later consumption. Orb weavers employ external digestion, injecting digestive enzymes into the wrapped prey to liquefy its contents. The spider then sucks up these liquefied nutrients, as their digestive system is too narrow to process solid food.
Dietary Variations
An orb weaver’s diet can vary based on factors like the spider’s size and species. Larger orb weavers are capable of catching and consuming larger prey, occasionally including small vertebrates like frogs or hummingbirds, though such occurrences are rare and opportunistic. The availability of different insect types in a particular geographic location or habitat also influences the spider’s diet. For instance, spiders living near outdoor lights may capture more nocturnal insects.
Web architecture, including mesh size and overall web dimensions, affects the types and sizes of prey captured. Some species specialize in trapping certain insects due to their web design. The nutritional quality of available prey can impact a spider’s web-building frequency and the physical properties of its silk. These variations highlight the adaptability of orb weavers in securing sustenance.