Western Black Widow - Latrodectus hesperus

Moved

Moved from Widow Spiders.

… Andrew Williams, 7 February, 2010 - 5:07pm

Moved

Moved from Spiders.

… Andrew Williams, 30 January, 2010 - 6:12pm

Looks odd

It looks more like a southern black widow to me, but that doesn't make much sense with your location.

… Lynette Elliott, 28 January, 2010 - 9:41am

… Andrew Williams, 28 January, 2010 - 1:37pm

i thought the same too - southern

Our data shows Southern in OK and TX, not too far from CO. Here in KC I've only seen northern so far. I wonder if they could have been introduced? I've got a pic of another one from neighboring suburb eating an earwig. I think you can see the bottom of it. Will try to dig that pic up. Solve the Denver black widow sp. :)

This part half matches, half doesn't. The western males I've seen were never black overall like this one.
"Males of the western black widow have three diagonal pale stripes (matches) on each side of the abdomen and are usually light brown (doesn't match), whereas males of the other species of Latrodectus are generally black (northern, southern)."

… Andrew Williams, 28 January, 2010 - 10:06am

I've read, reread

looked at images and looked again. I still think this 'looks' like a Southern Black Widow, male. I don't know how much the patterns can vary... maybe this one is just an odd duck. As far as I know Southern Black Widows aren't supposed to be found that far west.

EDIT: Southern Black Widows are found in CO.

… Lynette Elliott, 28 January, 2010 - 8:13pm

bizarre

I checked the link you suggested. There are existing records for Western BW in Golden/Jefferson County. The CO Southern records are interesting, spread out both in time and geography, one was out on grassland, so I assume wild/native. I wonder if this "colony" of what looks like Southern BWs could have been introduced at this park? I found them on the bathroom buildings not far from the parking lot, hiking trail beginning. I'm adding the park name to location. To me this looks like a Southern BW male, not like any of the Western I've seen. Now I'm staring at the Northern black widow pictures, getting more confused. :)

EDIT - I posted at canadianarachnology.org. Some views, but no replies as of yet. I think this is a good mystery.

… Andrew Williams, 28 January, 2010 - 10:19pm

Andrew. It is a subadult male L. hesperus. The basal band (the u or boomerang shaped band behind the head) is unique to the species.
The band is split in adult mactans http://bugguide.net/node/view/34225/bgimage and
http://bugguide.net/node/view/85345/bgimage, although in heavily marked adult variations the borders sometimes connect in the middle giving the appearance of a complete band. That is not the case here, however.

The broken dorsal stripe forming several spots is most likely regional variation as opposed to a unique specimen.

Compare linked images to adult male hesperus
http://bugguide.net/node/view/13101/bgimage.

… Jeff Hollenbeck, 7 February, 2010 - 2:53pm

thanks Jeff

I appreciate your input on this. I'd never seen a male Western BW that looked like this. Mystery solved then :) Did you have any thoughts on the other image I took the same day, the emaciated looking widow. Female, or Male Western? It's the thumbnail I pasted into the original post, above.

… Andrew Williams, 7 February, 2010 - 5:06pm