John Bokma Pet scorpions
freelance Perl programmer

Comments: Scorpion detection using UV LEDs


Note: UV light can seriously harm your eyes.

Read the rest of Scorpion detection using UV LEDs.



You should look for Insectia2 Scorpions HRHDTV DivX6 AC3 www mvgroup org avi . Stars noted entymologist Georges Brossard, and that particular episode deals with Scorpions and there's a bit in the desert where he goes searching for them with a UV light. Scorpions - the ONLY arachnids whose fossils actually glow under UV too !!!


Posted by GG at 01:11 GMT on 3 March 2006

UV or Blacklight is the heat wavelength, so the scorpion is feeling the heat, literally, but from the top rather than the bottom.

Posted by Hawkeye at 14:24 GMT on 1 April 2006

Hawkeye, My best guess is that the scorpions either see the blue light (or maybe near blue) that those LEDs generate as well, or maybe the greenish glow of their own body.

As of the heat wavelength, an interesting read is: Infrared light is not a kind of heat.

I doubt that the very bright UV light is sufficient to heat up the scorpion though.

Posted by John Bokma at 17:13 GMT on 6 April 2006

Wow, that is pretty cool! No scorpions in the North (Michigan) that I know of, but I wonder if it works on other creepy crawlies too.

Anyway, you mentioned your leds get quite hot while operating. This is a bad thing - led lifespan and light output is severely diminished by overheating. They should remain cool while operating, if they feel at all warm, you're giving them too much power, or in the case of your setup, you're demanding too high of an energy density for the level of thermal management your design provides. In other words, too many LEDs too close together. Can you add a fan or something, to cool the leds down... have it blow on the back of your circuit board - this will get you more light from each LED, and preserve their lifespan.

take care, justDIY

Posted by justDIY at 13:23 GMT on 7 April 2006

@justDIY: yeah, the LEDs got hot because the power source I used, when in 12V mode it actually it provided almost 16V. I know that some supplies give a bit more when not under much load, but not that much. I also assumed the load of the LEDs was sufficient enough to even drop a bit below the 12V.

As of scorpions in Michigan, only stow aways or so I understand. And as far as I know, scorpions are the only creepy crawlies that light up under UV.

Posted by John Bokma at 19:39 GMT on 17 April 2006

Ants, bees and I assume many others as well see with short wavelength light. (blue or longwave uv). I had always assumed since scorpions are nocturnal they were an exception - seems not.

The human eye has persistance and will see the peak power of a pulsed array - that is to say you can get a perceived brighter light with the same average power by varying its duty cycle. The LED has a peak power rating as well as just average disappated power (thermal). I remember HP as one of the first companies to use this phenomena to save battery power in their calculators.

Posted by Kirk at 14:28 GMT on 2 July 2006

Hi, John. You came up first for "UV scorpion" on google. My wife has wanted to enlighten/scare the grandchildren with a UV light at a popular lake in Nevada at night. I went overboard and got a 390nm UV light from Xenopus. In for a penny, in for a pound. It's nice to see you come up first on google for my scorpion search. Any idea if it will work with solifuges ? We'll find out :-)


Posted by Leonard Blaisdell at 05:01 GMT on 11 July 2006

Scorpions are not the only arthropods to fluoresce - some sowbugs and moth pupae do so as well. When scorpions molt, the shed skin retains the ability to fluoresce, but the scorpion has to wait for about 48 hours to regain its fluorescence. Apparently the material that is fluorescent is only in the cuticle. It appears that this may actually be caused by calcium salts that are stored as waste in the outer integument and may have little to do with any real function. In other words, it may be accidentally fluorescent. Some researchers, however, think that scorpions may be able to perceive UV light, in which case it might have some function. We just do not know enough yet.

Posted by Anna at 18:41 GMT on 3 September 2006

I note the paper was written 3 years back. Now I see many types of UV LED flashlights for sale on Ebay and elsewhere. I wonder whether hte 380-385 nm LEDs would work as well or better than the 395 nm ones? I don't think they were available 3 years ago.

Posted by Beaters at 18:10 GMT on 10 September 2006

Do ALL scorpions glow under a blacklight? i have only ever seen the Emperor ones...

Posted by Sean at 18:10 GMT on 3 January 2007

Hi Sean,

Some scorpions seem to glow very faint, and I have seen one or two species mentioned not to glow at all. Can't recall the names though, I'll try to look it up later.

When a scorpion has just changed it's outer skeleton it takes some time for the new skeleton to glow again. Also I've read that exposing the scorpion to a lot of UV light reduces the effect.

I keep several species, and they all glow, except when they just changed "skin". Even their cast-off skeleton (skin) glows under UV. I like to show this to people when they visit our house. Most have seen scorpions (Mexico) but never have seen this effect.

Posted by John Bokma at 01:50 GMT on 16 January 2007

@Anna: you're correct. In one terrarium I keep a scorpion and it has a dead sowbug in it, and it indeed does glow faintly.

And I have the impression as well that scorpions are able to preceive UV light: when I use a normal flash light they are not bothered much, however, they walk out of the UV light after a short time and go into hiding.

Many thanks for your very informative comment.

Posted by John Bokma at 01:50 GMT on 16 January 2007

I have a piece of property in central texas with lots of scorpions. I think I'm going to try this little UV LED trick. What good are scorpions by the way? Can you eat them? I've thought about selling them on E-bay.

Posted by Leonard at 17:58 GMT on 6 July 2007

@Leonard: scorpions do eat crickets, roaches, and ... scorpions. If you start to remove scorpions too effectively, you might very well start another problem.

As for scorpion control: scorpions hardly can't climb smooth surfaces. Ensuring that all entries to the property have a smooth surface around is quite effective in stopping scorpions from entering.

Also, removing hiding places (boulders, piles of wood, etc) close to the property helps.

Scorpions are indeed eaten by people. I have never tried scorpion though (I have eaten grasshoppers in Oaxaca though, which were nice).

Posted by John Bokma at 18:38 GMT on 6 July 2007

Interesting that the scorpions seem to detect the UV. I've been using a small flashlight with 4 LED's that I converted several years ago, I use the 405 nm wavelength. I bought some of the 395 nm ones, but the 405's seem to work a bit better. Scorpions don't run away from my light, usually just sort of pull their appendages and tail in a bit. And with only four LED's I can still see a scorpion at at least 3 to 4 meters.

Love your site BTW!

Posted by gary at 16:23 GMT on 15 January 2008

Question: Can you spot a scorpions trail with the UV light? You know, where they've been, which way they are crawling too? If anyone knows, let me know. thanks.

Posted by Tee at 17:48 GMT on 29 April 2008

@Tee - no, not with UV ligth. Although from what I've read scorpions do leave a trail of chemicals on the substrate. It's how, for example, the male finds a female. Maybe it's possible to detect this trail with some dedicated device, but from what I understand the trail stays only detectable by another scorpion for a short time.

You might want to read Response of male Centruroides vittatus (Scorpiones: Buthidae) to aerial and substrate-borne chemical signals (Euscorpius, 12: 1-6) (PDF).

As for other ways of tracking scorpions, a few days ago I found the following article: "Screening for scorpions: A non-invasive approach to tracking the movements of arachnids in sand", see: Proceedings of the 3rd Scorpiology Symposium (Euscorpius, 17: 168.) (PDF).

I've plans to look further into the latter.

Posted by John Bokma at 21:18 GMT on 1 May 2008

Does anyone know if insects are likely to be attracted to a UV light? I'm planning an expedition to Borneo and was thinking of buying a UV head torch (the one I'm looking at is 380nM) but don't fancy getting dive-bombed by moths and so on...

Posted by Kerri at 16:06 GMT on 13 February 2010

Can't answer your question, but Borneo... wow. Did you read Into the heart of Borneo and/or Stranger in the Forest? I can recommend both books; great read.

Posted by John Bokma at 23:04 GMT on 17 February 2010

What would YOU do, if, on a dark night, you suddenly started glowing brightly?

I suspect you'd freak out, too....

But lots of insects do perceive UV, so why not scorpions? Although I don't know what advantage it might give them. Surely they haven't evolved to escape UV-flashlight-wielding curiosity seekers?

Posted by Bob Kerns at 11:44 GMT on 29 May 2011

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