Cuerna Critters: Our spectacular scorpions

A post for all those scorpion fans out there! We have a lot of scorpions here in Cuernavaca, and in the state of Morelos in general. There are at least 16 resident species, some of which are fairly benign and others that are pretty dangerous. The most venomous species we have here is Centruroides limpidus, with a LD50 as low as 0.69 mg/kg. For more on lethal doses, check out this post by Susan E. Swanberg over on SciLogs.

For the untrained eye (that would be mine), it’s not easy to tell apart the different scorpion species, so I won’t even attempt to put species labels on the following photos. I suspect I have scorpions from at least two of the genera found here, Centruroides and Vaejovis. If anyone out there is able to help me identify these guys (or gals  – I’m not sure how you determine the sex of scorpions without getting too close!), please leave me a comment. I’d love to give them names. I’ve also logged some of my observations on iNaturalist under the project ‘Arácnidos de México’ in the hopes of identifying them.

I’ll start with one from Jiutepec, Morelos – a municipality generally considered to belong to the larger Cuernavaca metropolitan area. The scorpion pictured below was dead when I found it. Interestingly, their tails often straighten like this when they die. I’ve also noticed this with specimens I’ve frozen for later photographing and identification. (Yes, I have a tupperware with dead scorpions in my freezer. Doesn’t everybody?)

Observed in Jiutepec, Morelos, Mexico.
Centruroides sp.

In Cuernavaca, we often find scorpions inside the house. Thanks go to my very brave husband, who catches them so I can photograph them safely. This usually involves placing a container over them, slipping a piece of paper or cardboard underneath to cover the opening, and flipping the container right way up to screw on the top. Note: I am only describing the procedure, not suggesting you try it. No, really…please don’t try this at home.

Unidentified. Observed in Cuernavaca, Morelos, Mexico.
Unidentified, possibly Vaejovis sp.?

Scorpions glow spectacularly under ultraviolet (UV) light. Check out this piece from Ed Yong on fascinating research into why scorpions do this. Their fluorescence is also useful for worried moms, checking under beds at night before the kids go to sleep. (I’m not paranoid – we have found scorpions under the bed more than once. ) At the height of our scorpion infestation,  – things have gotten a lot better since we started mopping once a week with a special liquid repellent – I kept a UV flashlight next to my bed to walk to the bathroom at night.



I took video of the above scorpion moving around in the capture cup under UV light.

The UV flashlight also comes in handy to check the path in front of you when taking the trash out at night. I now take the trash out only during the day.


Scorpion mothers carry their young on their backs, as shown in this amazing photo by Ingo Arndt. I’ve found what I suspected were baby scorpions based on their size, but I’ve only ever seen them wandering solo. They are amazingly tiny.

I unfortunately don’t have anything placed for scale here, but this baby scorpion was not much longer than my thumbnail.


Here is another baby (juvenile?) scorpion, with a car key placed for scale.


Most of the scorpions we find, however, are adults. Photographing them inside the glass jars we trap them in often makes for some cool reflections.



And because they can’t crawl up the sides, it’s safe to take the lid off the jar so I can get a closer look. The lighting on this shot came out strange, but I kind of like it.


I also have a plastic capture cup with a magnifying lid top, which is great for catching all types of critters. Here’s a scorpion we caught on our porch one morning.

DSCF7463_3Sometimes we catch more than one critter at a time. That day, the scorpion above shared the capture cup with what I guess is some species of cellar spider. Neither appeared to be very happy with this arrangement.

DSCF7538_1DSCF7481_2To give you an idea of scale, here I am holding the cup.

DSCF7495_3Sometimes when it rains, it pours (scorpions). The same day we caught the above critters, we found this one, too.


The inevitable question after seeing all these is, have you ever been stung? Fortunately not <knocks on wood>. The closest I ever came was while I was folding sheets one day. I usually shake them out first, but this time I didn’t and nearly put my hand right on this beauty.

Centruroides sp.

This scorpion was large, compared to most others I’ve found.

DSCF7947_4 DSCF7950_2


It was also much lighter in color than the ones we had previously seen. Popular opinion here is that the lighter-colored scorpions are the most dangerous ones, but I don’t know how accurate that is. Below is another scorpion we found with similar light coloration.

Centruroides sp.
Centruroides sp.


Scorpions are excellent hiders. See that fantastic exoskeleton on the right? Great. Now look to the left…and you’ll see the tail of the scorpion that shed it, tucked away under a gap in the roofing of this shed.


Yesterday, I found a tiny scorpion tucked into a hole on the end of a stick that my child had just picked up. <Cue moment of parental panic>


As a mom who is also a critter enthusiast, scorpions present a challenge for me. Of course I want to keep my kids safe. I need them to be able to identify these animals and be aware of the harm that can come to them if they get stung. I remind them to shake out their shoes before putting them on; to not reach into places they can’t see; to not go around poking under rocks; to call an adult if they see a scorpion. But I don’t want them to come away with the idea that scorpions are somehow ‘evil’, or become unnecessarily fearful. We talk about the fact that scorpions are just animals that in most stinging cases are simply trying to defend themselves. We talk about interesting aspects of scorpion physiology.  I think it’s important that I balance the warnings with positive information. In that way, they can both stay safe and appreciate how truly amazing these animals are.

Centruroides sp.
Centruroides sp.

10 thoughts on “Cuerna Critters: Our spectacular scorpions

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  1. WOW! Fantastic series of pics – one of my favorite critters of all time – in fact we were just discussing them here at home last night, love the post – cheers for all the work you’ve put into it … btw – Centruroides – would be my fav 🙂 … catch up soon eh?

    1. Thank you! Those Centruroides are amazing critters. Interestingly, that’s the only genus of the four found here that’s considered to be of medical importance.

      Definitely catch up soon 🙂 Readers, go check out the awesome critter pics on Garden Guests, while you’re at it!

  2. Interesting piece. I’m not a huge lover of scorpions, but as an ex-certified Vet Tech I can certainly appreciate them. Although my cats like to kill and leave them on the floor from time to time giving me a start. Came across your blog when I was looking at what types of scorpions were in Cuernavaca, Morelos so I knew which ones to worry about and which to shoo out of the house. And of course with cats, one cannot be too careful.
    You mentioned sexing scorpions, males have larger pectines (which are underneath the scorpion just before the last set of legs) which have more ‘teeth’ and provide a more comblike appearance than females. I worked with a few reptile specialists in the past and some of the most interesting facts tend to stick in my head even years later.
    Also have you heard/read of The Scorpion Files? It’s an interesting place and thought the more scorpion friendly people out there might like to take a look:

  3. I am discovering this years late – but in Cuernavaca you are near the Instituto de Biotecnologia of the UNAM. Talk to Lorival Possani, Alejandro Alagón or Gerardo Corzo!

  4. Hi, what is the name of special liquid repellent you talked about?, where can I get it?

    Thanks in advanced.

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