Q: What are Those Miniature Spiky Puffballs? A: Brown Widow Egg Sacs

September 22, 2012

Earlier this week, staff found some small circular egg cases on a gate in the North Campus. Upon closer inspection we realized they were brown widow, Latrodectus geometricus, egg sacs. But how did we know this?



Earlier this week, staff found some small circular egg cases on a gate in the North Campus. Upon closer inspection we realized they were brown widow, Latrodectus geometricus, egg sacs. But how did we know this?



 

Two egg sacs, each containing about 100 eggs,

notice the geometric design.

 

Differences between brown widows and western black widows:

Brown Widows

Egg sacs are pale yellow and spiky (BINGO)

Egg sacs contain upto 150 spiderlings (best word ever)

Can lay 20 sacs over their lifespan

Adult females are USUALLY tan with an orange hourglass design on the underside of the abdomen

Lower incidence of medically significant spider bites

 

Western Black Widows

Egg sacs are pale yellow and smooth

Egg sacs contain upto 300 spiderlings

Can lay 10 sacs over their lifespan

Adult females are black (duh!) with a red hourglass design on the underside of the abdomen

Higher incidence of medically significant spider bites

 

Visit UC Riverside's Center for Invasive Species Research site for more information on identifying Brown Widows.

 

Check out this video Sam Easterson made of a brown widow tending her egg cases:

If you want to meet a brown widow up close and personal, all you have to do is visit our Spider Pavilion. The pavilion opens to the general public Sunday September 23. We have both a brown widow and western black widown on display in tightly shut enclosures! Stop by and say hello.


(Posted by: Lila Higgins)

8 Comments

spiderlings is the best word ever

spiderlings is the best word ever

Great minds think alike!

Great minds think alike!

I saw these egg sacs at work and though they were wild! Not sure if posting a link in here will work, so if not and you'd like to see my photo (5 egg sacs AND the momma) let me know! http://s234.photobucket.com/user/isispisces/media/brownwidow_zpse17c7075.jpg.html

Look interesting. I thought http://proofreading-services.org/ this should be a very different thing. So, I was very surprised when I've read it all.

I meant to say that it looks interesting. I thought this should be a very different thing. So, I was proofreading-services.org very surprised when I've read it all.

And the last thing here is that it looks interesting. I thought this should be a very different [url=http://proofreading-services.org/]proofreading-services.org[/url] thing. So, I was very surprised when I've read it all.

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