Uroctonus mordax Breeding Report

In April 2008, I was presented with a female Uroctonus mordax that was caught 14 miles west of Corvallis, Oregon.

The female on April 10:

As time progressed, she was observed to have grown larger, and she was suspected to be gravid. Possible embryos were observed through her membrane between the tergites and sternites. She was checked on in early July and had not yet undergone partuition.

On the afternoon July 13, 2008, the female was found with a brood of first-instar scorplings on her back.

Brood size at this time was estimated at greater than 16 scorplings. Humidity was raised and the female was left undisturbed to avoid stress that may lead to cannibalism.

The scorpions were checked on periodically throughout the next week by holding a flashlight to the side of the enclosure and looking through gaps between the piece of cork they were hiding under and the substrate. As all that was seen was a pile of white scorplings, the cork was not removed.

On the evening of July 23, 2008, a similar check raised suspicions that the young appeared too well-developed to still be first-instar (though they were still very white). The cork was removed for a brief photography opportunity.

These photographs revealed that the young had indeed begun to molt into second-instar. Because they were still so pale, it was assumed that this had happened very recently and they had not yet started to darken (wild observations found dark specimens believed to be second-instar, though it is possible they were third).

Another check on the morning of July 26th showed only slight darkening, but revealed that some of the young had begun to scatter from the mother's back.

The final check occurred on the evening of July 31st, 2008, and revealed that all but three of the young had left the mother (one remained on her "face," one on her pedipalp, and one was hanging on underneath). Looking at the substrate and the cork that the young were hiding on gave a final count of 26 second-instar Uroctonus mordax.

The female was removed at this point to hopefully determine the communal nature of juveniles of this species, and prey (pinhead crickets) was offered at this time. No feeding has yet been observed.

The young were found to fluoresce at this point, so it is assumed that their exoskeletons have finished sclerotization.

Basic timeline:

April 2008: female acquired
July 13: brood discovered
July 23: 2I discovered
July 26: slight darkening of young, scattering started
July 31: young completely scattered, mother removed, prey offered

Updated Collection

Since I've started this blog, I had quite a few deaths but I also gained a few scorpions. Here's an updated list of the species I have:

Scorpions
---------
0.1.0 Androctonus amoreuxi
2.0.0 Androctonus mauritanicus
0.1.0 Centruroides hentzi
0.0.1 Centruroides margaritatus
0.1.0 Centruroides vittatus
0.0.1 Diplocentrus lindo
0.1.11 Hadogenes paucidens
0.1.0 Hadrurus arizonensis
0.1.8 Heterometrus longimanus
0.0.5 Hottentotta judaicus
1.0.0 Mesobuthus martensii
1.1.0 Pandinus cavimanus
1.0.4 Pandinus imperator
0.1.0 Paruroctonus boreus
0.0.1 Paruroctonus gracilior
0.4.17 Uroctonus mordax
0.1.0 Vaejovis coahuilae
1.2.0 Vaejovis spinigerus <-- very gravid

Tarantulas
----------
0.0.1 Brachypelma smithi
0.0.1 Grammastola rosea
0.0.1 Avicularia purpurea

Other Arachnids
---------------
0.0.1 Mastigoproctus giganteus
0.1.0 Damon sp.
0.4.3 Latrodectus hesperus
0.0.5 Latrodectus geometricus
0.2.~ Steatoda grossa

Myriapods
----------
0.1.0 Archispirostreptus gigas
0.0.1 Ethmostigmus trigonopodus
0.0.1 Scolopendra subspinipes (HK Giant morph)

Cockroaches
------------
Blaberus fusca
Blaptica dubia
Blatta lateralis
Gromphadorhina portentosa
Nauphoeta cinerea

Vertebrates
-----------
1.0.0 Elaphe guttata
1.1.0 Felis silvestris

The snake in theory belongs to my fiancee, but I always feed it because she's kind of squeamish about that. I should also be able to trade one of my Androctonus mauritanicus sometime next month for a female.

Uroctonus mordax to 2I

I've been checking on my Uroctonus mordax brood almost daily the past week, but I'd only been checking by holding a flashlight to the side of the container and looking underneath mom's hide from the edge of the tank. Each time I saw white, assumed nobody had molted, and put the light away until next time.

When I looked tonight, I thought I saw more definition to the scorplings than usual, so I risked removing the hide for some photography. And what do you know? They've begun molting to second instar!
Compared to my photo from last week, you can see that there's less "pudge," and they were also eager to scurry from mom's back at my disturbing them. In the next photo, you can see one of the molts on mom's carapace.


Either this species remains white at 2I, or I caught them recently enough that no one has had a chance to darken.

I'm thinking of removing mom from this container when the young scatter and trying a "juvenile community," to see if it's like emperor scorpions (juveniles do fine together) or bark scorpions (juveniles happily snack on each other). As these are forest scorpions, I'm hoping for the former, but I have heard of cannibalism in this species when different sizes were kept together.

Update from 7/26: More have molted and began to darken up.

Uroctonus mordax Brood

While checking on and feeding my invertebrates today, I discovered I was correct when I thought my largest female Uroctonus mordax was gravid.

I counted at least 16 scorplings, with more possibly buried underneath. For those of you who aren't aware this species is native to the Pacific Northwest. This particular specimen was collected around 14 miles west of Corvallis, Oregon, in the Coast Range.

Here's a modified version of the above photo to better show the babies:

West Texas Scorpions

So I just got back from an invertebrate excursion to West Texas, and I managed to bring back a few scorpions with me that I just got IDed by Kari McWest. (If you don't know who that is, he's one of the biggest names in the scorpion field, especially with taxonomy.) First up are a couple Vaejovids.

This is Paruroctonus gracilior, found near the famous Marfa Mystery Lights. Forgive the picture quality, but this guy is tiny. I have a feeling it's immature (I forgot to ask Kari how big the adults get). We found several of these hiding in the crown of a small grassy plant that was growing in the area.


Next up is another Vaejovid, Vaejovis coahuilae. There were a lot of Vaejovis species around, and I forget which came from where, but I think this one was found near Ft. Davis. Most were found blacklighting at night while they were wandering around the area. A few were spotted flipping rocks during the day.


And finally, Diplocentrus lindo. These guys have got some real attitude for being so small. Also collected near Ft. Davis.
We also found a couple Centruroides vittatus. I didn't manage to get any good photos of the female I got, but I might post some later. She was collected near Sanderson.