Have you ever wondered how to know if a spider you’re seeing or keeping as a pet is pregnant or not? I was asking myself the same question and was able to find the answer to this exact question which I will share in this article. After I’ve shared an in-depth answer to the main question I’ll also give answers to a few related questions you might want to know the answers to as well so make sure you keep reading.
How do you know if a spider is pregnant? The first sign of a pregnant spider is when its abdomen is enlarged due to possible pressure from inside but you can only be sure once you see the spider making an egg sac because a bloated abdomen can also mean that the spider has recently consumed a large meal.
What does a pregnant spider look like?
One of the largest signs that a female spider is pregnant is when the spider’s abdomen is enlarged. But if you want to know for sure then you should check if there is an egg sac nearby the female spider which will confirm that she is pregnant.
As mentioned as an answer to this question, a sign of a female spider being pregnant is when its abdomen is enlarged which you can see in the image below.
An enlarged abdomen doesn’t necessarily mean that the female spider in question is pregnant though and that’s why it’s important to look out for an egg sac that will confirm the spider being pregnant. Below you can see an example of a spider with an egg sac.
What is an egg sac?
Spiders are oviparous animals which means that baby spiders won’t develop inside the spider but through a structure called an “Egg Sac”. The female spider uses its silk to create the egg sac so that the baby spiders can develop nicely and safely.
Egg sacs are usually round, smooth, and woven to be typically close to the same size as the spider that creates the egg sac. An egg sac can therefore be seen as closely related to cocoons that, for example, moths make which also spin with silk.
How does a spider make an egg sac?
Spiders have an organ in their body that can be used to create silk which is called a “spinneret” and at the underside of the spider’s abdomen are “spinnerets” located which are typically segmented. With these spinnerets, the female spider will make her egg sac.
The majority of the spiders have six spinnerets but they can also have two, four, or eight. Apart from that, the spinnerets can move independently from one another and at the same time as well. When the silk is still present in the spider’s body it will remain liquid and once it leaves the spider’s body through the spinnerets then the silk will become solid.
What does a spider egg sac look like?
Egg sacs are flat or round shaped. They are typically the size of the spider that created them. The color of the egg sac can also differ from a close to white color to a brown color depending on how many baby spiders are present in the egg sac and also on the spider species that laid the eggs.
Below, you’ll see an image of a spider holding its egg sac.
If you can’t get enough of learning about spiders then I encourage you to check out the “Spiders Category Page” which consists of various articles that give answers to spider-related questions.
How many baby spiders can emerge from an egg sac?
A spider egg sac can hold between 4 and 600 baby spiders depending on the spider species that laid the eggs. Every single time a spider is pregnant it will mostly lay a different number of spiderlings.
Also, a lot of spiderlings will not survive their first hours on this earth, so it’s great that it’s likely that a lot of spiderlings will emerge from every egg sac.
How do spiders get pregnant?
A male spider has a pair of appendages which are called pedipalps. The pedipalps of the spider can produce sperm and are therefore inserted in the female’s reproductive openings which are located on the underside of the abdomen of the female spider.
Before this all can happen, the male spider will need to first find a receptive female spider. Once the male has found a receptive female, he’ll first deposit his sperm on a sperm web (which he holds in his pedipalps) before slowly moving closer towards the female spider.
How long do spiders stay pregnant?
Spider eggs take between 30 and 50 days to develop once they are put into an egg sac. The number of days until the “spiderlings” will come out of the egg sac depends on the spider species that the spiderlings are, the current season that it is, and also on the current temperature.
So, as you can read different factors will affect how long spiders can stay pregnant.
How does a spider give birth?
The female spider stores the sperm of the male spider (which can be kept good for up to two years). Once the female spider is ready to use the sperm it will fertilize the eggs with the stored sperm and then the female spider will create an egg sac where the eggs will be deposited in.
And once the spiderlings have had enough time to develop, they’ll bite through the egg sac and enter the world.
How do you know if a Wolf Spider is pregnant?
The obvious signs of a Wolf spider being pregnant is if it either has an enlarged abdomen or if you’re able to locate an egg sac close to the spider in question. Besides these facts, Wolf spiders usually get pregnant during the summer days.
The eggs will take between 20 to 40 days to come out of the egg sac.
How do you know if a Black Widow spider is pregnant?
The Black Widow spider will either have a large abdomen or an egg sac close by to tell if the spider is pregnant or not. Besides this, the eggs of the Black Widows will come out between one and four weeks.
So, just like pretty much all the other spider species, Black Widows spiders will also show the obvious signs when they’re pregnant.
How do you know if a Garden spider is pregnant?
The Garden spider creates an egg sac if she’s pregnant and the spider will also have an enlarged abdomen before laying its eggs. An unfortunate but natural occurrence is that the female Garden spider usually dies after giving birth as its job has been fulfilled which is to reproduce.
So, if you run into a dead female Garden spider, it can be the case that she has just given birth to her spiderlings.
How do you know if a Brown Recluse spider is pregnant?
The Brown Recluse spider will either have an enlarged abdomen or an egg sac near her to tell if she’s pregnant or not. Usually, egg sacs of the Brown Recluse spider can be found at the end of spring or during the summertime.
Make sure you don’t disturb Brown Recluse spiders though when you see an egg sac with them as they will defend it with their lives.
How do you know if a House spider is pregnant?
The House spider will create many egg sacs throughout its lifetime and just like all the other spider species it will either have a large abdomen or an egg sac close by which will reveal if it’s either pregnant or not.
Even though house spiders are less dangerous than Brown Recluse spiders, you should also not disturb house spiders as they’ll defend their egg sacs heavily as well.
How do you know if a Jumping spider is pregnant?
Female Jumping spiders can produce between 2 and 36 eggs in one egg sac and you can find out if the Jumping spider in question is pregnant by checking if there is an egg sac close by the spider or that she might be pregnant if she has an enlarged abdomen.
As you’ve just read, jumping spiders can’t produce that many eggs in one egg sac when compared to many other spider species.
How do you know if a Huntsman spider is pregnant?
The Huntsman spider can lay up to 200 eggs in one egg sac and you’ll be able to see if the spider is pregnant by checking if there is an egg sac near the spider or that it might be pregnant by checking if the abdomen is enlarged.
So, as you’ve just read huntsman spiders can lay a lot more eggs than jumping spiders can and they’ll show the obvious signs that many other spider species show when they’re pregnant.
What happens when you kill a pregnant spider?
Depending on how much the spiderlings have developed, it can happen if the spider gets squashed by your foot that some of the further developed spiderlings will start running. It is unlikely that any of the spiderlings will survive as they are most of the time underdeveloped.
It can also happen that the spider just dies without being squashed and in this case, the spiderlings won’t have any opportunity to run as there won’t be a way out.
Below, I’ll share a video of what can happen when you squash a pregnant spider with your shoes.
How to get rid of a pregnant spider?
What you could do is get a jar, or, for example, a piece of paper and make sure you get both the spider and if present the egg sac and put them in the jar or on the paper to easily put them outside. The pregnant spider and its spiderlings will thank you for it!
So, make sure you choose this option above potentially killing the pregnant spider.
How do you kill a pregnant spider?
I’d encourage you not to kill the spider and instead of killing it, catch it in a jar (together with its egg sac) and put the spider together with its egg sac in your yard or somewhere further away from where it won’t be able to find its way back to your home.
In my opinion, this is the best way because if you kill the spider you can be sure that you’ll kill at least the spider and a decent number of its spiderlings which would be a shame. You should also keep in mind that if you kill the pregnant spider that spiderlings could emerge and run in different directions which is probably also not what you’re looking for.
Related questions
Why do spiders carry babies on their backs?
In particular, Wolf spiders carry their babies on their backs because it provides extra protection for their just born spiderlings. Besides this fact, Wolf spider spiderlings will also latch on to other body parts of the female Wolf spider if the back happens to get too crowded.
Do spider babies eat their mother?
This can indeed happen and the spider species “Stegodyphus Dumicola” (commonly seen in South Africa) is a great example of this phenomenon. This article will go more in-depth if you’re interested but in short, it’s a way of providing the mother’s spiderlings a better chance of survival.
Can you move a spider egg sac?
It is possible to move a spider’s egg sac but it is not recommended as you could accidentally put a hole in the egg sac and encourage the spiderlings to come out early which is probably not what you want as you want to move it without the spiderlings emerging. If you need to move it, do it gently!
Summary
Now you know that a pregnant spider will either have an enlarged abdomen (which doesn’t assure that the spider is pregnant as it can also have had a big meal recently) or it will have an egg sac close by which will assure you that the spider in question is pregnant.
You also know that the egg sac is a ball of silk that has been created by the female spider as spiders are oviparous animals which means that the babies of the spider won’t develop within the spider but through eggs.
You’ve found out that spiders have an organ named a spinneret which is used to produce silk. The spider also has multiple spinnerets located on the underside of the spider’s abdomen which are segmented and can be used independently from one another or at the same time. With the spinnerets working together, the spider can produce an egg sac whenever the time is right for the spider to do so.
You now know that the number of spiders that can emerge from an egg sac is between 4 to 600 spiderlings and that female spiders get pregnant through the pedipalps of male spiders by inserting the pedipalps into the female’s reproductive openings.
You also know now that the spiderlings take between 30 and 50 days to develop within the egg sac and that the female spider can decide when she will use the sperm of the male spider to create the egg sac (as the sperm can be kept good for up to two years).
Then I shared with you that pretty much every spider species is going to have either an enlarged abdomen to see if the spider is pregnant or that it is going to have an egg sac close by which will be the only defining factor to know for sure that the spider is pregnant or not.
You know that killing a pregnant spider will surely result in the female spider dying and also at least most of the spiderlings dying in the end as they likely will be too underdeveloped to care for themselves. It is best to never kill a pregnant spider, you should instead gently put it outside together with its egg sac if you want to get rid of the spider and its future spiderlings.