Chronicling the life cycle of Joro Spiders, across two generations
I watched an adult Joro Spider protect her egg sac. After she died, I waited four months to watch the birth and growth of her baby spiders. In this blog, I’m logging and sharing images and videos of their journey.
The Joro Spider (Trichonephila clavata) is an invasive species in the U.S. that hitched a ride on a container shipment from either Japan or China about 11 years ago and landed in a heavily warehoused region north of Atlanta. From there, this hearty spider multiplied, and the rest is history. If you live in northern Georgia, you have come to accept that these scary looking, 3-inch spiders, who are docile and harmless will be a part of your life. I decided, if I can’t beat ’em, join ’em. So, I’ve been watching these girls closely for years (the big, beautiful ones are always the female, the male is small and brown). This year, I was lucky enough to spot an egg sac in an easily accessible place for monitoring. I knew the mom well. She was a 6-legged spider, who lived on the side of my house for the entire typical length of a Joro life cycle in Georgia (April through November or December).
October 6th, 2024: This was the mom, I named her “six” (real creative). You can see which legs are missing because the coxa (the socket where the leg attaches to the body) is still there, but no leg. The missing legs are the first leg (by her head) on your left, and the third leg on your rigth.
November 11, 2024: Towards the back end of her life cycle, she lays her eggs. “Six” was diligent about protecting her eggs. In this video she is building protective web around the eggs.
November 11, 2024: The video below is from the same day, it does a better job of showing how she created the web. Every time you see her “butt” come up, and her back two legs going to the butt…that's her pulling the web from her “spinneret” and attaching it to the rest of the web she has built. If you look closely, at certain times in the video you will see two bumps or protrusions at the backend of her abdomen (basically what I’m calling her butt, which it isnt). Those two protrusions are her spinnerets, and this is where she shoots her web from. Because it's up against a light background, it's hard to see the web on the video, but you can easily see what she is doing. Very cool.
November 28, 2024: Eventually “Six” dies in late November, maybe a week or two earlier than a few other Joro's around the outside of my house. But her work was done, and a well-protected sac sits. And we wait…
And wait…
And wait…
And wait…
The egg sack stays well protected through the winter. Occasional below freezing temperatures don’t alter anything. Between December and April, it doesn't appear that any predators or storms caused any damage. My research suggests that they will hatch around April. I visit the eggs every day, starting on April 1st. My chronic pessimism tells me that there is no way this will actually happen, that these vulnerable and tiny creatures won't actually sit there dormant for months and then do what they’re supposed to do at the beginning of spring. But I check every day. April 1st, nothing. April 2nd, nothing. April 3rd, 4th, 5th…nothing. And nothing continues for a few more days. But on April 9th, the sac looked different. I can't see movement or hatching, but it looks odd.
April 9, 2025: Something happened over night. If you compare this picture to the one above, it’s obvious that something went down over night. I don't see anything move, but stuff is happening. If you look at the red egg furthest to the bottom, you’ll see a white/translucent spider shaped figure, but it was still. everything was still.
April 10, 2025: They are hatching! My patience (not a strength of mine) pays off, as I got to witness these little creatures making their way out of their eggs after being dormant since November.
Here are two videos showing two different spiders trying to pry their way out of their egg. I’m not a spider expert, but by watching these Joros as long as I have over the years, that red bulbous “body” isn’t their body, it's the egg they are trying to climb out of. This is all filmed using my iPad, so not the best quality.
On April 11th, they all started poppin’
April 12, 2025: My cat thinks my spider hobby is becoming a problem.
April 18, 2025: Eight days since the first Joro hatched, and there are still big differences in the stages of hatching and development between spiders. In this video, you can see one spider who is much further along, walking around, and has some color, but the left is a fresh new-born still trying to separate itself from its egg and join the rest of the spiders. They don't all make it. One of these spiders is a couple of days old, the other is still not 1 day old yet. Look how their coloring changes in a matter of days. They are both so small, it's hard to even detect movement with the naked eye, they look like a speck of dust.
April 19, 2025: Here is some perspective on the size of a 9-day old Joro. They will reach 2.5 to 3 inches by fall when they are full grown. The egg sac isn't much larger than the tip of my finger.
April 20, 2025: Its Easter! 10 days from the first spiders to hatch, there is still a lot of movement around the (Easter) egg sac and many spiders haven't ventured out yet.
Days go by, and it's a lot more of the same. Some hatching, some struggling, some walking around half hatched, and some learning their web skills. Here is one of the spiderlings looking quite ungraceful with its web work. I like to think this is analogous to a baby learning how to walk.
At this point, I'm checking every day, just waiting for a milestone…waiting for something, anything cool to happen.
Waiting…
And waiting…
And waiting…
Then on April 26th, I walk up the egg sac, and there's nothing there. No spiderlings, no babies hatching, no movement. They’re gone. But then I look up about two feet above the egg sac, and I see something dark. I don't have my glasses on, and I'm not on my ladder yet. (I failed to mention, I'm standing on a ladder for all of this). I get on the ladder and climb higher than I've had to in the past (it’s just step ladder), and I get closer and eureka! something new has happened. A huddled mass of bodies and legs, not moving. Just a bunch of siblings resting and snuggling after moving away from the sac.
This was really cool, since I didn't know what to expect to happen as they started to grow up. Another analogy to relate this to humans. I think of this transition from the egg sac to their new location 16 days after hatching, similar to a baby coming home from the hospital into their new nursery. To this point, I have been very intentional to only watch, never disturb, never get involved. But I thought, just once I want to see what this ball of spiders does with a slight puff of my breath comes their way. A quick and light blow…
This startled me a little bit, to be honest. I expected a little movement, but they rewarded me with a show — the spider version of a firework exploding in the sky.
I expected them to eventually come back together into their cluster, but I didn't know how long it would take. I decided it might be worth it to record a time-lapse and see what happens. And come back together they did! These 19 seconds of time-lapse covers about five minutes of time.
April 29, 2025: We have our third milestone! Milestone 1 — they hatched on April 10, milestone 2 — they left the egg sac 16 days after hatching, and now at about 20 days old, milestone 3 — these spiderlings are going through their first molting. As Joro spiders grow, their hard exteriors don't grow with them, so they have to leave their old bodies to make room for their new bigger bodies. A Joro will go through this process multiple times in their life cycle. Some of the spiderlings will die during the molting process because it puts a lot of stress on the body. This is normal. Spiderlings will also die from dehydration or predators. I've seen research that says the survival rate of a brood is as low as 10% and as high as 30%. but with hundreds of Joro's per sac, plenty will make it to adult hood. In this video you will see what looks like little dead spiders at first glance, but those little translucent ghost-like bodies are the former bodies these spiders have separated themselves from. Tiny little Joro ghosts now share the web with these growing spiders. There are two very active spiders in the video, one on top and one on the bottom. I'm not positive, but what I think they are doing is trying to molt and leave their bodies.
Here is a better look at what their former bodies look like after they have been left behind. The silvery and translucent outer bodies even have the legs intact.
Over the next two days, I noticed an increase in activity. Prior to the 30th when I would visit, they were usually in their typical ball resting. Even the molting that occurred was mostly overnight, so they days weren't that active. But on the April 30th and May 1st, their behavior shifted, and they were busy — maybe excited to have their new larger bodies, maybe getting restless and eager to explore the world. Joro's will generally “balloon” away from their nest when they are ready to leave. “Ballooning” is when a Joro shoots is web into a breeze. Once the web extends long enough, and it becomes heavier than the spider, the wind will pick it up and the tiny spiderling will parachute into its forever home. During these two days of high activity, I noticed three different spiders decide to make their home on my ladder. They ended up in the woods after I removed them and carried them away on a stick. This video from April 30th at 20 days old, shows a typical scene from these two active days. Its early morning, bad lighting, poor quality, but it gives you an idea what those two days looked like.
May 2, 2025: The two days of activity culminated in the 4th milestone. And that 4th milestone was moving out. They all left over night. Of course it’s possible something else more sinister happened, but their web was undamaged, and some of the eager spiders over the previous two days were indicating the rest of the group might be ready to leave soon. All that remained were the ghostly reminders of their molted bodies, a few of which I recovered for examining under a microscope.
With “Six’s” babies all moving out, it was time to move my ladder back into the garage. Right as I went to fold it up, I found one final Joro from the bunch, making its home on my ladder. This one had grown to about a half a centimeter. as I have done to the others, I took a stick and started to encircle the spider, picking it up and all the web around it. Joro’s being pretty calm spiders, will usually just walk on to the stick, making it easy to carry them down to the woods. This one decided it was going to spin its web, and slide down to the ground. I saw her walking towards the wall of my house. My hope is she remains and builds her home right back where she started. I want to see Six’s grand children next April.
This is the end of the first chapter of their lives…. their birth, hatching, making their first web, molting, and then leaving — walking or ballooning away on a breeze and landing where they will set up their next and final home. Eventually, one large, yellow, black and red female, and one tiny brown male spider per web will start to show up all around the yards, trails, power lines, road signs, bushes, porches, and fences of northern Georgia.
This is also the end of the first chapter of this blog. I will inevitably have many Joro spiders around the yard, and hopefully that one remaining ladder spider from the brood to watch and share their spider journey with you.
Stay tuned as I chronicle the lives of some adolescent and adult Joro spiders. We are just getting started…
