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Black Widow With Egg Sack - Latrodectus mactans - female

Black Widow With Egg Sack - Latrodectus mactans - Female
Russellville, Pope County, Arkansas, USA
September 4, 2005
Size: ~4cm
Black widow guarding her egg sac. Found and photographed in central Arkansas

Nice shot.
Interesting markings on it's back.

Black widow
Thanks Lynette;

I'm no expert, but my readings on these spiders seemed to indicate that the red back markings are more common on the southern widow than the northern version.

This one had a "squat-looking" hour-glass belly mark, whch I believe is also characteristic of the southern variety.

She may have been a youngish female.

Going through the Latrodectus images...
Terry, nice image!

Do you happen to remember if the hourglass was solid:

or broken?

This would confirm the species. Southern black widows have a "solid" hourglass whereas the Northern black widows have a "broken" hourglass.

Belly marking
Hi Chris!


The belly marking was a solid, but squat-looking hourglass.
It looked like your top image, but was not quite as elongated in the middle. Definitely not "broken" like the northern.


Great! L. mactans it is!
I moved this to the Southern Black Widow image page (Latrodectus mactans). Thank you for sharing! (especially since your image is a little different than the other images; your specimen clearly has the red markings on the top of the abdomen and a clear picture of the egg sac.)

From what I understand, there is some variation in the length of the hourglass mark, so the broken/solid hourglass is the best way to ID. There is actually another species of widow in your area, the brown widow (L. geometricus, info), which is strongly believed not to be dangerous, but the egg sac is wrong for the brown widow. :)

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