I've noticed a bizarre pattern, am I crazy

[CRX]

So I was smoking in my garage just now, and like always I look up at the ceiling above and watch the spiders. Today, i realized, not only was there a community happening, it was inter-species. So theres this elevated gap that goes across my entire garage ceiling if that makes sense, I will post a pic in next reply. And it is filled with spiders, but they have an order to it. I swear to god. There is an order. Each ones space is usually exactly a foot apart. It goes pholcid, pholcid, pholcid, steatoda, steatoda, pholcid, steatoda, pholcid. They all are nesting in the exact same spot not far from each other. Is this just because its cold? Central Kentucky

Here's the area I meant, along the green line. That top area. They all have evenly spaced apart webs. If you look closely you can see some of them lol

 

[Charliemum]

Here's the area I meant, along the green line. That top area. They all have evenly spaced apart webs. If you look closely you can see some of them lol
View attachment 487076

I have both these living in my house in close quarters too. I think as long as there is enough food they are more then happy to share a space, it's not till the food runs out will the cellars take out the steatoda. There is probably plenty of food in your garage with the car coming in n out .

 

[Brewser]

Garage Spiders behaving quite civilized...
until Someone crosses the Line.

 

[The Snark]

@CRX Not seeing much in the way of pideys but you got a recent replacement what appears to be a foam core FRP all weather 10 or 12 foot 4 panel track door with single torsion spring, cable lift and a 1/4 or 1/3rd HP power opener. Tracks are hung on an old doors braced hardware. You can adjust the top panel a little to close more tightly to the header beam.
Thieves know a trick of reaching a wire in the gap between door and header and snagging the opener release cable. Give it a tug and open up the door.

 

[Ultum4Spiderz]

So I was smoking in my garage just now, and like always I look up at the ceiling above and watch the spiders. Today, i realized, not only was there a community happening, it was inter-species. So theres this elevated gap that goes across my entire garage ceiling if that makes sense, I will post a pic in next reply. And it is filled with spiders, but they have an order to it. I swear to god. There is an order. Each ones space is usually exactly a foot apart. It goes pholcid, pholcid, pholcid, steatoda, steatoda, pholcid, steatoda, pholcid. They all are nesting in the exact same spot not far from each other. Is this just because its cold? Central Kentucky

Here's the area I meant, along the green line. That top area. They all have evenly spaced apart webs. If you look closely you can see some of them lol
View attachment 487076

Weird coincidence!!!! All I see are seller spiders in the basement.

 

[CRX]

@CRX Not seeing much in the way of pideys but you got a recent replacement what appears to be a foam core FRP all weather 10 or 12 foot 4 panel track door with single torsion spring, cable lift and a 1/4 or 1/3rd HP power opener. Tracks are hung on an old doors braced hardware. You can adjust the top panel a little to close more tightly to the header beam.
Thieves know a trick of reaching a wire in the gap between door and header and snagging the opener release cable. Give it a tug and open up the door.

Hhahahah yeah we did get it about a year ago. Thanks for the tip, ill let my parents know.

 

[Glorfindel]

need to zoom in or get closer to spiders, I cant see them from ceiling picture.

 

[CRX]

need to zoom in or get closer to spiders, I cant see them from ceiling picture.

Yeah I couldn't get any closer lol. You can see the spiders, but they just look like black dots

 

[The Snark]

I'm going to venture a guess of cannibalism dividing up the area of the ceiling. Both Steatoda and pholcid like corners to attach their webs. As time goes on and they mature the pholcids will eat the steatoda where the webs mingle and likely you'll end up with just them. Pay attention you might get a ring side seat as to how capable pholcids are when it comes to combat with other species. Let the population evolve the pholcids are communal sharing guy lines of neighboring webs and mature males will often attract females to share their webs.
The general competition scenario is steatoda and nearly all cobweb weavers rely on sticky lines to initially trap prey. Pholcids keep to their own or neighboring pholcid webs. They can tell which is a pholcid from other species of webs. Pholcids don't have sticky lines. They wrangle the prey while staying well clear of the enemy, employing their back four legs to tie up their victims. So they easily outclass all other species of spiders entering their webs. Salticids in their roaming are very commonly victims to pholcid battle tactics as they can't negotiate webs at all.

Fascinating. When a pholcid has a victim each of the back four legs snag some silk from the spinnerets and try to loop it over the victim. This is FAST! All four back legs can be active doing the looping in a fraction of a second.

 

[AphonopelmaTX]

I can't explain why, but it is common that pholcids live next door to theridiids. I frequently see the cellar spiders find the webs of the cobweb spiders, kick them out of their own webs, and live in them for a while before moving on.

I have attached a picture of a couple sharing space, but not webs. However, the webs were joined together. There was no way to get clear images of the spiders as well as showing the full extent of the space they occupied so you will have to take my word for what family they both belong to.

 

[CRX]

I can't explain why, but it is common that pholcids live next door to theridiids. I frequently see the cellar spiders find the webs of the cobweb spiders, kick them out of their own webs, and live in them for a while before moving on.

I have attached a picture of a couple sharing space, but not webs. However, the webs were joined together. There was no way to get clear images of the spiders as well as showing the full extent of the space they occupied so you will have to take my word for what family they both belong to.

View attachment 487314

Looks exactly like the setup in my garage.

 

[AphonopelmaTX]

Looks exactly like the setup in my garage.

I looked back at some of my documentation to get some more info. The picture I posted was from July 20, 2020 and forgot I e-mailed the American Arachnological Society e-mail group about it because both the cellar spider and cobweb spider both had babies right next to each other at roughly the same time with no predation events observed. I asked if it was common and whether there was some sort of relationship between the two different spiders, but I didn't get much of a reply other than the relationships are dynamic and one will invade the web of another (or not). My take-away was that it was a common occurrence and that sometimes the cellar spider will eat the cobweb spider and sometimes not. Nothing I didn't already know from my own observations. Although the most common prey in the cellar spider webs were small flys and other unidentifiable insects while the most common prey for the cobweb spiders were male spitting spiders. I never actually saw a cellar spider eat a cobweb spider, but that doesn't mean it didn't happen when I wasn't looking.

What was interesting is that I had two different species of cellar spider at that location: Pholcus phalangioides and something else. I can't find my notes on what that "something else" was, but it was much smaller and had a different eye arrangement than P. phalangioides. It is one of those situations where I would know the genus if I saw it. Anyway, I only saw P. phalangioides associated with the webs of the cobweb spiders and never that other cellar spider species so it appears to be unique to P. phalangioides where I live. I have since moved from the location with all of that spider activity, but I still see the same thing occurring at my new place during the summer. P. phalangioides really like to bully those little cobweb spiders but never actually eats them.

Here is a close-up photo I found, which was sent to the American Arachnological Society, of the same cellar spider in the previous photo with her babies. The color of the wall is different in this photo because I had the flash on (as indicated by the original image's metadata). I couldn't get a good picture of the cobweb spider babies because they were too tiny, and the corner too dark, for my phone to pick up.

 

[Brewser]

I Totally Agree, Another one of 'Lifes Little Mysteries'

 

[The Snark]

I can't explain why, but it is common that pholcids live next door to theridiids. I frequently see the cellar spiders find the webs of the cobweb spiders, kick them out of their own webs, and live in them for a while before moving on.

From observation, Pholcids are opportunistic without being outright predatorial. They expand their webs and welcome fellow Pholcids as neighbors. I have yet to see them predate others of their genus. But their continual expansion brings other species into contact with their webs. Then it's either move out or become potential Pholcid prey.
Over a period of four years we started with two Pholcids at the ceiling of our bathroom. They eventually bred and expanded until all four corners of wall meets ceiling was their webs occupied by 20-30 mature and countless offspring making their own webs often integrated with the adults.
(That bathroom was ideal for the Pholcids. No screens and well ventilated with the septic tank vent just outside. The house itself isolated with fallow fields and rice farms on all four sides.)