HCA: Hermit Crab Association

Hey everyone! I'm new to this forum (in fact I just joined today due to this exact problem), so I'm not sure how everything works yet. However, this is kinda urgent.
Yesterday night, I saw a lot of TINY, pinprick, nearly microscopic white bugs crawling in and around my crabs' tank--they even were all over the top of my dresser, where I keep the crabs. I'm super worried for my crabs' health, and I have been thinking about rehoming the crabs since this is the second infestation of this exact kind of bug in less than 3 months. Does anyone know what bugs these are, if they're harmful, and cleaning instructions on how to get rid of them?!

Can you post a photo?
Using Tapatalk is easiest but other apps can also be used.

curlysister wrote:Can you post a photo?
Using Tapatalk is easiest but other apps can also be used.

Sorry that took a while, had to figure out how to use the app lol.


it’s not a very good picture, but they’re less than 1 mm, i’d say .5 mm or less. i tried to post a video, but it didn’t want to work lol.


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These are 100% grain mites. When the population reaches critical mass, they start spreading out from wherever they were at. It's a known issue with mealworm breeders!

Thank you so so much!! Sorry for excessive questions, but are they harmful to the crabs? Do you just get rid of them by a substrate change, tank/decoration boiling/bleaching, and baths for the hermit crabs? That's what I've done in the past but I'm not certain if that's the correct way to fix the issue!

They are harmless. Here's the info sheet all about mites:

viewtopic.php?f=124&t=92530

Thank you so much for the help!!

My only concern is how many there are, as they may not slow down anytime soon. Mealworm farms get them because the worm bedding is made of grains and is a pure food source for them. Our crab tanks will have some food, but not usually enough to support this many. They can eat cocofiber and wood, but generally not to this extent. I would recommend being conservative with food amounts. Avoid fresh fruits if possible, and dried banana.

If you really want them gone, I would suggest predatory mites. It's the only thing that will actively pursue them inside and outside of the tank, and once the grain mites are gone then the predatory mites eat each other out of exsistance. I would be afraid with this many that even a good solid clean won't help in the least because they will find their way back quickly.

wodesorel wrote:My only concern is how many there are, as they may not slow down anytime soon. Mealworm farms get them because the worm bedding is made of grains and is a pure food source for them. Our crab tanks will have some food, but not usually enough to support this many. They can eat cocofiber and wood, but generally not to this extent. I would recommend being conservative with food amounts. Avoid fresh fruits if possible, and dried banana.

If you really want them gone, I would suggest predatory mites. It's the only thing that will actively pursue them inside and outside of the tank, and once the grain mites are gone then the predatory mites eat each other out of exsistance. I would be afraid with this many that even a good solid clean won't help in the least because they will find their way back quickly.

Oh okay, that makes sense. Thanks for the advice!


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I just wanted to say welcome! I know everyone else was focused on answering your questions.

Oh, thanks!! This seems like a great website!