There are no true winged spiders. Spiders belong to the class Arachnida, which includes scorpions, mites, and ticks. They are fundamentally different from insects (class Insecta), and this taxonomic distinction explains the absence of wings. The idea of flying spiders is a misunderstanding stemming from the biological limits of the arachnid body plan and the aerial dispersal method some spiders employ.
Why Spiders Cannot Develop Wings
The development of wings is linked to the specific body structure of insects, an anatomy spiders do not share. Insects possess a three-part body structure: a head, a thorax, and an abdomen. Wings always grow from the thorax, the middle section dedicated to locomotion.
Spiders, conversely, have a body divided into only two segments. The head and thorax are fused into a single unit called the cephalothorax (or prosoma), which is attached to the abdomen. This fusion means spiders lack the distinct, segmented thoracic structure needed for wing attachment and the internal musculature required for powered flight.
Another fundamental difference is the number of legs: insects have six, while adult arachnids have eight. In insects, both the six legs and the wings are anchored to the thorax. Spiders, with their eight legs attached to the cephalothorax, are constrained by an ancient body plan that lacks the anatomical space for wing formation.
The existing respiratory system of spiders, which relies on book lungs or tracheae, would also face challenges supporting the high metabolic demands of sustained flight.
Spiders That Travel Through the Air
Although spiders cannot fly, many travel vast distances through the atmosphere using a passive dispersal technique called ballooning or kiting. This behavior is most common in small species, particularly spiderlings, who use this method to migrate to new habitats. The spider climbs to a high point, such as a blade of grass or a fence post, and raises its abdomen into the air.
The spider then releases fine strands of silk from its spinnerets, which are carried away by air currents. Once enough silk is airborne to generate sufficient drag and lift, the spider lets go and becomes airborne. This process allows them to travel tens or even hundreds of miles; historical accounts, such as those by Charles Darwin, document mass ballooning events far out at sea.
Recent research suggests this aerial travel is not solely dependent on wind currents, but also utilizes the Earth’s natural atmospheric electric field. The Earth’s surface and the atmosphere create a global electric circuit, which results in a naturally occurring positive electrical charge in the air. Spider silk, being an insulator, picks up a negative charge, causing the silk threads to repel one another and the ground.
This electrostatic repulsion provides a measurable lift force, acting much like a sail or a kite. The spider senses the strength of the electric field using specialized sensory hairs on its legs. This allows it to initiate take-off even on days with little wind, explaining how spiders are sometimes observed rapidly launching under seemingly calm conditions.
Common Spidery-Looking Flying Insects
Much of the confusion surrounding winged spiders comes from misidentifying flying insects that have a spindly, long-legged appearance. One common culprit is the Crane Fly, an insect often mistakenly called a “daddy long legs.” These flies belong to the family Tipulidae and are true insects, possessing a clear head, thorax, and abdomen, along with a single pair of wings.
Another source of confusion can be certain species of parasitic wasps or long-legged gnats that have dark, slender bodies and wings. These insects adhere to the six-legged structure of their class, which immediately distinguishes them from any arachnid. Their appearance can lead people to incorrectly assume they have encountered a winged spider.
By contrast, the true arachnids often called “daddy long legs,” known as harvestmen (Opiliones), do not have wings. Unlike spiders, they have a fused body that appears as a single oval structure. Flying insects that resemble spiders are easily identified by observing their anatomy: if the creature has wings and six legs, it is an insect, not a spider.