Flying Spiders

Flying Spiders - Can Spiders Fly?

There have been mentions of flying spiders moving from one location to another. It leaves you wondering, since when do spiders have wings?

Well, flying spiders don’t have wings. Instead, they practice aerial dispersal through a method known as ballooning. Spiderlings often use aerial dispersal methods to move from their birth location to a new one. This move is necessary because it gives them a better chance of survival and reproduction. 

Related: Whereas technically spiders aren't insects, flying or otherwise, you might also like our ladybug facts and cool bug facts.                         

The Mechanics of a Flying Spider

Crab Spider
A crab spider - a species of "flying spider." Photo by Erik Karits on Unsplash

There are no types of spiders with wings. The process of flying spiders moving through the air is called ballooning, but we mainly refer to it as flying. Ballooning spiders often called flying spiders, move by releasing silk strands that catch in the wind, leaving them to propel their way through air currents and electric fields. As such, they move differently from winged birds and flying insects in the air. 

A group of scientists conducted extensive research on ballooning between the years 1926 to 19314. They devised an airplane trap system for the analysis that allowed them to catch insects in the upper air. They collected 28,739 insects in Louisiana and 1,294 in Mexico. Out of these insects, they caught 31 spider species and 1461 spiders, respectively.

In their observations, they found certain species of both adult spiders and baby spiders let out long silk threads acting like anchors. The webs can reach altitudes of up to 11 000 ft. The group of scientists suspected arachnids transported themselves with the help of the wind, using the silk thread as web parachutes. 

Spiders fly without wings by climbing onto an elevated surface, like twigs, the top of trees, or a fence. The flying spider then stiffens its legs and exposes its abdomen to an estimated angle of 45 degrees. Then, depending on its weight, it spins out a web or series of webs. The flying spider lifts itself off the ground and seemingly glides through the air as the wind catches these webs.

Not all flying spiders balloon successfully.

Sadly, not all ballooning trips are successful. Some webs anchoring the flying spiders get blown away when the wind current is too strong. Also, elevated objects can interrupt their flying. For example, there are multiple reports of flying spider webs on ships miles away in the middle of the ocean and on flying balloons. 

However, scientists noticed some flying spiders could control their movements at will. A flying spider regulates its movements by drawing in its claw and forming a ball web. This method leads to a slow or sudden stop.

Flying spiders, commonly found in northern continents, require meteorological conditions like air speed, humidity, temperatures, and an uplifting breeze. Different types fly under varying conditions. For instance, the wolf spider prefers to fly in atmospheric conditions with lower humidity and high temperatures. Also, most flying spiders prefer to balloon during the day when these conditions are most favorable. 

Apart from the environmental factors that affect ballooning, the flying spiders’ individual behaviors are also a factor. Flying spiders get the urge to glide when looking for a new, suitable habitat when they are experiencing food shortage and overpopulation. 

The Electric Field Theory of a Flying Spider 

There were two proposed theories regarding the mechanism of ballooning in the early 1800s. The first theory was about the support of the breeze that helps lift the silk webs, and the second theory referred to the electrostatic forces in the atmosphere. Charles Darwin started questioning the possibility of flying spiders on the 31st of October when he found thousands of tiny, red spiders on a ship 60 miles away from the shoreline.

The aerodynamic theory doesn't explain the mechanism of flying spiders completely, and scientists haven’t tested out the involvement of electrostatics. Electrostatic forces have an evident impact when aerodynamic forces are in motion. For instance, flying spiders spread their silk webs in a fan shape instead of tangling in the atmospheric currents. Each strand of silk was in a separate position, showing the action of repelling electrostatic forces.  

It then leads to the question, how can the flying spiders spin ballooning silk in low atmospheric currents? Because flying spiders need an external force to pull the silk from the spinnerets for spinning. 

Researchers Erica Morley and Daniel Roberts found that the global atmospheric electric unit and the resulting atmospheric potential gradient (APG) provide an additional force that helps these flying spiders balloon5

Their research explored is if spiders could detect and use electric fields worldwide. They placed adult Linyphiid spiders on a vertical cardboard strip in the middle of a polycarbonate box. The box limited the amount of airflow and served as an atmospheric potential gradient simulator. 

The spiders tested in this field showed pre-ballooning behaviors, showing that they can detect e-fields. However, electrostatic forces might not be a regularly necessary factor in ballooning. So Erica and Daniel proposed at least three functions of APG. These functions are:

  1. An indicator of climate conditions
  2. An informational trigger
  3. A physical driving force for ballooning

The test explains how flying spiders glide through various atmospheric conditions. The earth is a negative electric force field, while the atmosphere is a positive electric force fold. As spiders eject their long silk webs, it latches on to a negative charge. The webs' negative charge attaches itself against the ones on the forest floor, allowing flying spiders to lift themselves into the air. It explains why they climb onto the tips of twigs, leaves, and grasses. They climb on elevated surfaces to increase the electric force field around them to propel themselves higher. 

However, we must conduct more research about flying spiders and their interaction with atmospheric electricity. It will effectively help us understand the full mechanisms of flying spiders. Understanding this will also assist us in learning more about the transport of nutrients, pathogens, agricultural pests, and their natural predators between ecosystems.

Species of Flying Spiders 

Over 1000 types of spiders fly in the air. However, this aeronautical habit is most common to the:

  1. Orb weavers
  2. Subfamily Erigoninae of Linyphiidae
  3. Crab spiders

Orb weavers 

Closeup of a spiny orb weaver
Closeup of a spiny orb weaver. Photo by Wendy Aros-Routman on Unsplash

Reports of flying aren't common in orb weavers species. However, their geographic locations suggest otherwise. You will mostly find the Golden orb-web spiders in locations only possible through ballooning, despite the large size of the female spiders. 

Also the gray cross spider, also known as the bridge spider, is a type of orb weaver. Gray cross spiders prefer to stay on bridges, hence the name bridge spiders. They’re also known for their ability to stay afloat on water.   

Scientists tested baby spiders that weigh less than 1mg. Scientists refer to the golden orb weaver as an excellent disperser on almost all islands except remote islands like Hawaii and Polynesia. 

A group of scientists conducted a laboratory experiment to test the golden orb-web spider's ballooning abilities. They tested 59 spiders at two different wind speeds2. The spiders didn’t show any sign of pre-ballooning behavior at the average speed of 3.17 MS-1. However, 53 spiders showed pre-ballooning behaviors at an average speed of 2.17 MS-1, and 17 spiders out of the 53 that showed pre-ballooning behaviors eventually ballooned.

Subfamily Erigoninae of Linyphiidae 

Dwarf spider of subfamily Erigoninae. Photo Credit: Judy Gallagher (CC BY 2.0)

There are over 4000 small spiders in the family of Linyphiidae. Also known as sheet weavers or monkey spiders, they are the second largest family of spiders of the arachnids. These spiders are all flying spiders. However, their small size makes them susceptible to unsuccessful ballooning experiences caused by turbulent weather and microclimate. 

They have little to no control over where or how they land. So, it leads to the death of adult and baby spiders. However, ballooning helped these flying spiders with their wide distribution worldwide.

Crab spiders 

Male white crab spider
Male white crab spider. Photo Credit: Jean and Fred Hort (CC BY 2.0)

Crab spiders glide hundreds of miles, reaching places some insects with wings would not reach. Scientists and researchers analyzed what enabled them to travel long distances at a stretch1. They concluded it was about the hairpin vortices created around the silk threads by air turbulence. During the testing stages, they discovered the flying spiders’ webs contained between 6 to 15 ft of silk strands, and they were about 323 nanometers wide. 

Wind flows through the silky strands, creating turbulence that transports them. They concluded that pre-ballooning behavior is a means of testing wind speed

What is pre-ballooning? 

A pre-ballooning behavior is essential to the flight of a flying spider. It shows whether a spider is capable of airborne dispersal, aka flying. A flying spider exhibits pre-ballooning behaviors when it shows signs of rafting or tiptoeing. The spider raises its front legs and spins silk, which helps them hang upside down and swing within the embrace of the airflow until sufficient winds uplift helps stabilize its movements.  

Flying spiders that don’t use spider silk to fly

Apart from flying spiders that use their silk threads to glide through the atmosphere, some flying spiders move through the atmosphere without using silk parachutes. A group of scientists discovered that these other spider species move their legs in various manners to accommodate their descent into surrounding trees. 

The scientists dropped spiders from a distance and watched as ground-dwelling spiders fell with extended legs and reoriented themselves dorsoventrally. Also, they didn't show any signs that they could control the direction of their movements. 

Selenops spiders descended head first and reoriented themselves dorsoventrally using their aerial right reflex when necessary. They spread their front legs towards the front of their body while spreading their other legs sideways and towards the back. 

The scientists further reported that the flying spider's legs repeatedly twitched while it was gliding through the atmosphere. These flying spiders jump and glide away from predators with their forelegs. However, their directional control is difficult to determine, but they have more control than flying spiders that perform aerial descent3.

Selenops spiders have an excellent aerial posture. Most of the flying spiders landed successfully on their first try, although the study couldn't determine the spiders’ landing techniques. 

Are They a Threat to Humans?

Humans are afraid of the various species of arachnids and other bug-like creatures. We fear them because of the harm and pain bites from these creatures can cause us. Some spiders are venomous, while others aren't. 

Some flying spiders can produce venom used to incapacitate their prey. However, humans don't have any cause to worry about these flying spiders because their bites aren't powerful enough to kill or cause us any major injury. At most, the spot they bite will swell for about two weeks before it heals. 

There are no reports of flying spiders biting humans, despite the closeness of our interactions. Spiders only bite humans when they feel threatened in their webs. The only problem you will encounter from flying spiders is their webs dropping as they move from one location to another. There have been incidents of white webs covering fields and spots around human civilization, but we can easily sort this out with cleaning. 

Conclusion

Flying spiders are one of the fascinating creatures in the world. It also scares humans that spiders can fly like we are afraid of flying cockroaches. However, don’t fear flying spiders because they don’t threaten humans. They save their bites and venom for their prey. Even if a spider bites you, it will swell and heal within two weeks.

You can relate ballooning to the human activity of migrating from one place to another to live a better life. Once young spiders hatch from their eggs, they balloon away so their other siblings won’t eat them. Male flying spiders fly in search of fresh territory and potential mates. So, don’t kill them whenever you see them. 

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1

Cho M, Neubauer P, Fahrenson C, Rechenberg I (2018) An observational study of ballooning in large spiders: Nanoscale multifibers enable large spiders’ soaring flight. PLoS Biol 16(6): e2004405. https://doi.org/10.1371/journal.pbio.2004405

2

Lee VMJ, Kuntner M and Li D (2015) Ballooning behavior in the golden orbweb spider Nephila pilipes (Araneae: Nephilidae)Front. Ecol. Evol. 3:2. doi: 10.3389/fevo.2015.00002

3

Yanoviak SP, Munk Y, Dudley R. Arachnid aloft: directed aerial descent in neotropical canopy spiders. J R Soc Interface. 2015 Sep 6;12(110):0534. doi: 10.1098/rsif.2015.0534.

4

Glick, P. A., & United States. (1939). The distribution of insects, spiders, and mites in the air. Washington: U.S. Dept. of Agriculture.

5

Erica L. Morley, Daniel Robert, Electric Fields Elicit Ballooning in Spiders, Current Biology, Volume 28, Issue 14, 2018, Pages 2324-2330.e2, ISSN 0960-9822,

Jen’s a passionate environmentalist and sustainability expert. With a science degree from Babcock University Jen loves applying her research skills to craft editorial that connects with our global changemaker and readership audiences centered around topics including zero waste, sustainability, climate change, and biodiversity.

Elsewhere Jen’s interests include the role that future technology and data have in helping us solve some of the planet’s biggest challenges.

Photo by Erik Karits on Unsplash
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