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Armadillidium vulgare


This blue Roly-Poly, Pill Bug or Woodlouse has light dots down the top and three short stripes on each section on each side. The video shows the black one unrolling then shoving the blue one away in what seemed to be a territorial issue until I learned the reason for the blue coloring (see Notes)


Underneath a flat rock in the backyard.


"There is a type of virus called an “iridovirus” that attacks terrestrial isopods (roly polys or pill bugs) and forms crystals beneath their external skeleton (shell or cuticle). The accumulation of these crystals causes their appearance to change from the normal gray or brown to a bright blue, violet or purple. The virus is not dangerous to humans and cannot be “caught” from the roly poly." - Natural History Museum. "Sick pillbugs turn bright blue. Like other animals, pillbugs can contract viral infections. If you find a pillbug that looks bright blue or purple, it's a sign of an iridovirus. Reflected light from the virus causes the cyan color." -

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Sorry to hear so many were infected but what a sight that must have been!

MarkFrazier 10 years ago

Moving my wood pile today, I noticed about 1/2 were bright blue. First time I have ever seen this. It appeared that the infected ones were all larger in size than those of the normal color. - Location, Kansas City, Missouri.

Hi Katie, I added a couple links regarding the iridovirus in the notes section.

Thank you for the comment ikissedameow!

Katie Jenkins
Katie Jenkins 11 years ago

I found on recently here in Southeastern Virginia. Can you point me in the direction of the virus you mentioned?

ikissedameow 11 years ago

Great photos!I never knew they could turn blue when ill.

CindyBinghamKeiser 12 years ago

Thanks Gabi and KiKi :)

Kiara Robinson
Kiara Robinson 12 years ago


CindyBinghamKeiser 12 years ago

Thank you!

Scott Frazier
Scott Frazier 12 years ago

Beautiful! Moved to arthropods :-)

textless 12 years ago

Really interesting, and the video is great!

AnnvanWijgerden 12 years ago

Yes, it looks like the black one is saying "Go away! I don't wanna get sick like you!" :-}

CindyBinghamKeiser 12 years ago

I figured it out! This woodlouse/pill bug/rolly-poly has a virus causing it to turn blue. The video shows the healthy one pushing the sick one way in what I originally thought was a territorial issue.

CindyBinghamKeiser 12 years ago

Yip, this pretty one was in my little exotic piece of land in California :-) I've seen one before but it's been years!

CarolSnowMilne 12 years ago

I just have the usual dark kind. This is amazing!

Small Wonders
Small Wonders 12 years ago

Love the color!

julia11cc 12 years ago

Was that realy found in the U.S.A.?? Beautifull!!

San Diego, California, USA

Spotted on Nov 10, 2011
Submitted on Nov 10, 2011

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