How Can You Tell if a Spider is Pregnant?

How can you tell if a spider is pregnant?

How Can You Tell if a Spider is Pregnant?

If you’re curious to know if a spider is pregnant, there are a few signs to look out for. Firstly, you may notice that the spider has become more extensive. This is because the spider’s body expands to accommodate the eggs and the developing spiderlings inside. Secondly, you may notice that the spider is behaving differently than usual. Pregnant spiders are less active and may spend more time in their web or hiding in a dark area. Lastly, you may notice the spider producing a sac or egg case. This sac is where the spider will lay her eggs and can indicate that the spider is pregnant. However, it’s important to note that not all spider species produce egg sacs, and some may carry their eggs on their body. If you’re unsure if a spider is pregnant, observing it from a safe distance and avoiding disturbing it is best.

There are a few key signs to watch for when determining if a spider is pregnant:

• Abdomen enlargement: The spider’s abdomen will become noticeably more prominent and rounded as her eggs develop. This is usually the most obvious sign of pregnancy.

• Web changes: Some pregnant spiders will make significant changes to their webs, such as building egg sacs or strengthening their existing traps, to prepare for laying eggs.

• Positioning and behavior: Pregnant spiders may position themselves in some regions of their webs and behave differently, such as hanging still for extended periods. This helps conserve energy as they near egg-laying.

• Species instincts: Some spider species have specific egg-laying behaviors that indicate pregnancy, such as species that create egg sacs before laying their eggs inside.

• Molting delays: Many spiders delay molting (shedding their exoskeleton) while pregnant since molting disrupts the growth of their eggs. So, a lack of molting can signal a female spider is gravid (carrying eggs).

How do you know if a spider has eggs?

There are a few signs that can indicate if a spider has eggs:

  1. Abdomen size – If a female spider’s abdomen suddenly becomes much more significant and rounder, it likely means she has eggs inside. This is because spider eggs occupy most of the space inside her abdomen.
  2. Web changes – Some spider species will alter their webs when they have eggs. They may wrap the egg sac in silk for protection, attach it to the web, or make other changes.
  3. Guarding behavior – After laying their eggs, some female spiders will stay close to the egg sac and guard it vigilantly. She may coat the sac in more silk, wrap her legs around it, or remain nearby.
  4. Prey reduction – Some spiders will stop hunting for food after laying eggs, instead relying on stored resources within their bodies. This is to focus their energy on protecting the eggs.
  5. No longer receptive to males – Female spiders that have already mated and laid eggs will often no longer be receptive to male spiders trying to mate with them.
  6. Actual egg sac – Sometimes, you may see the spider’s egg sac attached to its web or elsewhere. The egg sac will be a small, ball-shaped cluster of white to pale yellow eggs enclosed in silk.

How do you tell the difference between a pregnant spider and a normal spider?

There are a few main ways to tell if a spider is pregnant:

  1. Size – Pregnant spiders are often noticeably more significant due to the eggs developing inside them.
  2. Shape – Some pregnant spiders, particularly orb weaver spiders, develop a more oval or pear-shaped abdomen than usual.
  3. Position of legs – Some pregnant spiders keep their legs further apart to accommodate the enlarged abdomen. This is most noticeable in wolf spiders and jumping spiders.
  4. Color – The color of some spider’s abdomens may change during pregnancy, often becoming lighter or translucent to reveal the developing eggs. This is seen in widow and recluse spiders.
  5. Behavior changes – Pregnant spiders may exhibit changes in behavior like spinning egg sacs, searching for safe places to lay eggs, staying in one location for extended periods, etc.
  6. Presence of egg sac – The most definitive sign of a pregnant spider is the presence of an egg sac that she created to contain her eggs. The egg sacs of different spiders vary widely in shape, size, and material.

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What does a pregnant spider do?

Spiders have a variety of different reproductive behaviors. Here are some things pregnant spiders may do:

• Lay eggs in an egg sac: Many spider species lay eggs in an egg sac or cocoon, which the female spider then guards and protects. The female may carry the egg sac with her or remain close by.

• Build a nursery web: Some spiders construct an elaborate nursery web to lay and guard their eggs until the spiderlings hatch. The nursery web provides a safe place for the eggs and young spiders.

• Produce a gelatinous mass: Certain spiders produce a gelatinous blob containing their eggs, which harden after being laid. The female may remain near the egg mass and guard it.

• Die after laying eggs: Some spider species are semelparous, meaning they die shortly after laying and guarding their eggs. This reproductive strategy ensures their offspring are maximally provided for.

• Protect and guard the eggs: Many pregnant spiders remain close to their eggs, acting as guards and protecting them from predators and the elements until the spiderlings hatch. Some even build canopies over the eggs.

Pregnant spiders perform various activities to care for and protect their eggs, including constructing special egg sacs or webs, remaining near the eggs, and actively guarding and defending the eggs until the spiderlings hatch.


Can male spiders become pregnant?

No, male spiders cannot become pregnant. Only female spiders have the reproductive organs necessary for carrying and laying eggs.

How long does a spider’s pregnancy last?

The duration of a spider’s pregnancy varies depending on the species. It can range from a few weeks to several months.

Do all spider species create egg sacs?

No, not all spider species create egg sacs. Some species carry their eggs on their bodies until they hatch.

Can you identify a spider’s species by its egg sac?

In some cases, yes. The appearance and structure of the egg sac can provide clues about the spider’s species.

Are pregnant spiders more aggressive?

While pregnant spiders may become more protective of their eggs, their aggression levels can vary from species to species. Some may become more aggressive, while others remain relatively passive.

What should I do if I find a pregnant spider?

If you encounter a pregnant spider, it’s best to observe from a distance and avoid disturbing her. Appreciate the fascinating natural process she’s a part of.


In the world of arachnids, understanding the signs of a pregnant spider can be both fascinating and educational. From abdominal swelling to the construction of egg sacs, these indicators offer a glimpse into the complex reproductive lives of these remarkable creatures. So, the next time you encounter a spider with a swollen abdomen or guarding an egg sac, you’ll better understand the miracle of spider pregnancy.

Remember to approach these creatures with respect and curiosity, appreciating the wonders of the natural world that are often hidden in plain sight.


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