Ballooning Spiders

Video-turned-gif of ballooning spiders in action.

Aerial migration is not limited to birds. It is also not limited to insects with wings. On any given day, there may be millions, or even billions of insects passing over head, and this vast collection of invertebrates often do include spiders. While possibly contrary to the belief of some, and given the right weather conditions, spiders can fly in a phenomenon known as dynamic kiting, or spider ballooning, and it is a phenomenon that Darwin recorded during his voyage aboard the HMS Beagle.

Two spiders attempting to launch on top a tall post.

Ballooning spiders disperse in enormous numbers, most often seasonally. Although they lack wings, they have their *silken threads that can passively carry them* on the wind. When it is warm enough for a thermal updraft and the wind isn’t too strong, some species of spiders, hatchlings and adults, climb to the top of a tall object. From there they face the wind, stand with abdomen raised, and release a silken strand or more known as gossamer. Once airborne, the spider rides the wind for possibly hundreds of miles and many, many days.

Ballooning isn't limited to a single spider species.

While thermal air currents play a role, it is possible that the electrostatic force is equally or more important in giving spiders a lift. It is currently believed that the force comes from a combination of the electrostatic field of Earth’s atmosphere, friction between the silk and dry air, and the rest from the spinning process and launch surface. Not only may this explain how heavier spiders launch themselves into the air, but it also explains how the silk threads fan out – negative charges repel.

More than one spider sometimes try to use the same launching grounds.

Whether to travel hundreds of miles or only a few feet, ballooning spiders is a notable phenomenon, especially when it is a mass of spiders taking advantage of a single good day of weather. A large enough event often times captures the attention of media, and even a reported sighting of a UFO was attributed to this phenomenon. In the end, it’s only some spiders looking for a new place to live.


This post is another rehash of an earlier Science Sunday post, but with a few different pictures. The original post can be found here along with an animation of ballooning spider launching mechanism (though it is slightly out-of-date). Do note that Thursday's post will be a bit different in that, for once, it'll be my Science Sunday post, but posted before that Sunday. Stay tune!