Spider Egg Sacs

Finding the Ray spider eggs this summer captured my attention and I began to seek out other spider egg cases and take photos. Below are the results of my finds so far.

The first one, Theridiosoma gemmosum, ray spider, was pretty much in plain sight hanging from a couple of branches on the side of the trail. It was a golden brown color but was hard to focus on and take a photo of because the silk reflects the light and the breeze kept it in motion. Eiseman and Charney in “Tracks and Signs of Insects” state that “the top of the sac is a separable cap, which is partly pushed off when the spiderlings emerge”. They also say that there are often many nearby but I didn’t know that at the time and didn’t think to look for others. They are in the family Theridiosomatidae and for an orb web that doesn’t have a hub but it tied together in the center and pulled together like an umbrella. Didn’t see that either but you can bet I will be on the lookout for it from now own. The shape of the spider is the typical fat round body like a Black Widow that most people are familiar with.

So when I came home from that trip I looked around the house and found these Common House Spider, (Parasteatoda tepidariorum) egg sacs and the spider to go with them. I have them all over the garage and deck so they were pretty easy to find. I just never paid them much attention before. The sacs look like little rolled up balls of brown paper bags. They hide during the day but can be found pretty easily in the evening. Most of the time I see one or more eggs sacs together. Their webs are messy affairs and the male often share the same web.

This a also a Common House Spider egg sac and some of the eggs hatched. Out they were near the screen door and I had to move them to another location. She didn’t seem to mind too much. I placed them on a paper towel in a safe location.

This next group was found on the side of the house and they look like they are made by a meshweb weaver (Dietnidae). They look right but I’m not certain of the size.



The Long-jawed orbweavers (Tetragnathidae) make an egg sac like the one above. It is fluffy and has green color silk added to it making it look like it has bits of moss and leaves added to it.  I also found some on the side of a rock at Valley Falls State Park.

I am certain of this one. It was made by a Neospintharus trigonu, a cobweb spider in the Theridiidae family. Problem was the wind was blowing too hard to get a good clear photo but you can still see the distinctive lantern shape. It is white when first made but then turn brown later.

These next two spider egg sacs I found along the river a couple weeks ago.



I believe they are from antmimic spiders (Corinnidae). Esieman and Charney say that Phrurotimpus can be brown to bright red. These along with several others were found on the under sides of over hanging rocks and mostly this color.

These next two can be confused but if you pay attention to where the egg sac is being carried you can identify it right away.

The Nursery Web spider carries the sac in her jaws until she finds a good place to to hide it just before the spiderlings emerge. The Nursery Web spider, in the family Pisauridae, is a good mother and is noted for protecting her offspring. She builds a nursery web around the egg sac before they emerge.

Above is the Wolf spider (Lycosidae) and it carries it egg sac attached to the spinnerets. It is made up of two halves. Lays down a flat layer of silk and lays the eggs, next she covers it with another layer of silk forming a ball. In this one you can see the two layers, one is darker than the other. She will open the sac when the young begin to hatch. Then they all crawl up on her back for 2-3 weeks until they are big enough to fend for themselves.

I once disturbed on in my basement and they all fell off. She waited for a few seconds while they all crawled back on. The one pictured above was in my flower box a few years ago. You can see the tiny spiderlings hanging on her back as she poses for this photo.

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