Small, white, spherical objects often appear in spider webs, prompting curiosity about their nature. These common additions to a spider’s intricate silk architecture are often misunderstood. Understanding what these white balls represent provides insight into the complex life cycle and behaviors of spiders.
Understanding Spider Egg Sacs
The most common white objects found in spider webs are spider egg sacs. Female spiders meticulously spin these protective casings from layers of silk to house and safeguard their developing offspring. The silk offers protection against environmental factors like desiccation, and acts as a barrier against predators and parasites.
Egg sacs vary in appearance depending on the spider species. They range in color from white, cream, or beige to brown, green, or yellow, influenced by silk type and environmental conditions. Shapes include round, oval, teardrop, flask-like, or disk-shaped structures, with textures from smooth to bumpy or spiky. An egg sac’s size is generally proportional to the spider that created it, often smaller than a quarter. The number of eggs inside can range from a few dozen to several hundred, or even up to a thousand, depending on the species; female spiders may produce one large sac or multiple smaller ones throughout their lifetime.
Other White Objects in Webs
While egg sacs are common, not every white object in a spider web is a collection of eggs. Other materials can also become entangled, leading to similar appearances, such as molted exoskeletons and wrapped prey.
Spiders, like other arthropods, possess a rigid external skeleton called an exoskeleton, which does not grow with the spider. As a spider grows, it must shed this outer layer through molting. The discarded exoskeleton, or exuviae, can often be caught in the web, appearing as a translucent, pale, and often crumpled white shell that retains the spider’s shape.
Another white, ball-like object frequently encountered in webs is wrapped prey. Spiders often immobilize or store captured prey by wrapping it tightly in silk. This creates a silk-encased bundle, which can appear as a white or off-white mass. The silk wrapping prevents escape, aids external digestion, and allows the spider to transport or store the meal. These bundles can vary in shape and density depending on the size and type of prey.
What Happens Next?
For egg sacs, the next stage involves the development and eventual hatching of spiderlings. After a period of development, which can range from weeks to months depending on the species and environmental conditions, spiderlings emerge from the egg sac. In many species, the first molt occurs inside the sac, with their small cast skins visible within the old sac after emergence. Once hatched, these miniature spiders, known as spiderlings, are often independent and resemble their adult counterparts, albeit much smaller.
Spiderling behavior post-hatching varies by species. Some spiderlings will disperse immediately by crawling away from the egg sac, while others engage in a behavior called “ballooning,” where they release silk threads into the air, allowing wind currents to carry them to new locations, sometimes over considerable distances. This dispersal mechanism helps prevent overcrowding and competition for resources. Some mother spiders, like wolf spiders, carry their egg sacs with them and may even assist in the spiderlings’ emergence, with the young climbing onto the mother’s back for a period.
Generally, spider egg sacs and spiderlings are not considered dangerous to humans in typical household or garden settings. Most common spiders are harmless, and their presence can even be beneficial, as they help control insect populations. If an egg sac is found indoors and removal is desired, vacuuming it up and disposing of the contents outdoors is a common method, ensuring it remains intact to prevent premature hatching indoors.