Spider egg sacs are protective silk structures created by female spiders to house their developing eggs. These sacs safeguard the eggs from environmental factors and predators. Within these silk casings, the eggs develop until they hatch into spiderlings. This structure ensures the survival of the next generation of spiders.
General Appearance of Spider Egg Sacs
Spider egg sacs commonly share universal characteristics. They are primarily composed of silk. This silk can be woven into various textures, ranging from smooth and papery to fluffy or spiky.
The sacs often appear round, oval, or pear-shaped. Their size typically varies, from as small as a pea to about the size of a marble. Most spider egg sacs are white, cream, or off-white in color, but some can exhibit tints of brown, yellow, or green.
Variations Among Common Spider Species
The appearance of spider egg sacs varies significantly between species, offering clues for identification. Black widow spider egg sacs, for instance, are typically round or pear-shaped, roughly 12 to 15 millimeters in diameter, and often off-white, tan, or gray with a papery texture. They may also have a spiky or rough exterior due to loose silk fibers.
Wolf spiders carry their spherical egg sacs attached to their spinnerets. These sacs are usually gray or tan. Garden spiders, such as the yellow garden spider (Argiope), construct pear-shaped or round egg sacs that are papery and brownish. These sacs are often suspended within the spider’s web or nearby vegetation.
Brown recluse spider egg sacs are flat, round, and loosely woven, appearing white to off-white. They are often hidden in undisturbed areas. Sac spiders create small, flat, disc-shaped sacs that are white and frequently found in folded leaves or corners.
Jumping spiders produce small, typically flat, white egg sacs, sometimes found under bark or stones.
Where Spider Egg Sacs Are Typically Found
Spider egg sacs can be found in various locations, depending on the spider’s habits. Indoors, common hiding spots include undisturbed corners of rooms, attics, basements, closets, and behind furniture. Spiders may also attach their sacs to window sills, door frames, or within their webs in secluded areas.
Outdoors, egg sacs are often located under rocks, logs, leaf litter, or in dense vegetation. They can also be found on fences, sheds, and under decks.
What to Do if You Discover an Egg Sac
Upon discovering a spider egg sac, identifying the species is helpful, as this informs the appropriate action. Many spiders are harmless, and their egg sacs, especially those found outdoors, can be left undisturbed as part of the natural ecosystem.
For egg sacs found indoors, particularly from potentially harmful species, safe removal is advisable to prevent an increase in the spider population. A common and effective method is to use a vacuum cleaner with a hose attachment to carefully suck up the sac.
After removal, immediately dispose of the vacuum bag or empty the canister contents into a sealed outdoor trash container to prevent spiderlings from escaping. Avoid directly crushing or handling the sac, as this might prematurely release spiderlings. If dealing with a known venomous species or a large infestation, contacting a pest control professional is recommended.