Are these grain mites?

tzpnm

Arachnopeon
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Oct 2, 2014
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Hi everybody,

For a long while now I’ve had these strange, white mites in my enclosures. They don’t seem to pose much of a threat, and I’ve never seen them swarming on any of my roaches or forming a cyst/dormant state (I forgot the name) on them, so I’ve been assuming that they’re harmless. For the longest time, they were getting out competed by springtails in most of my enclosures, but now the mites seem to have bounced back and the springtails have gone extinct in almost all of my enclosures. Anyways, I was wondering what kind of mites these are, their adults are about 1.5x the size of the largest Neoseiulus californicus that I introduced to control them (unfortunately haven’t seen a real reduction in the mite numbers, or any of the N. californicus for that matter). They are an off white, creamish color, and their heads are a darker color, closer to brown. They are easily visible to the naked eye, and up close it’s easy to identify their legs and mouthparts. In terms of speed, they are slightly slower than N. californicus, but they can run pretty quickly when they get agitated. Anyways, I’m not sure kind of mite they are, and if they are harmful or beneficial. They eat food waste and help clean up dead animals like springtails do, and they seem to occupy the same ecological niche, but I’m not sure what exactly they are or if they do anything extra that would be negative for my roaches/isopods.

Thanks for the help, and sorry for the lousy photos.
 

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The Snark

Dumpster Fire of the Gods
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Yup. They are. The bulbous abdomen and darker plate on the head is sort of a giveaway. The problem with these mites is they are essentially born pregnant* and the infants are light enough to disperse like dust. They will infest almost any grain or grain product as well as dried fruits, vegetable and dairy products and are nearly impossible to eradicate.
Grain Mite, Flour Mite, Acarus Siro

Image a drawing found uncredited in many publications all over the web.
* The male of the species usually doesn't eat. It remains around the ovipositor, inseminating the females as they emerge. They develop the 4th pair of legs at maturity and claw like spines which enable them to hitchhike on other insects. They are also known to transmit fungi spores attached to their bodies.
 
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tzpnm

Arachnopeon
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Yup. They are. The bulbous abdomen and darker plate on the head is sort of a giveaway. The problem with these mites is they are essentially born pregnant* and the infants are light enough to disperse like dust. They will infest almost any grain or grain product as well as dried fruits, vegetable and dairy products and are nearly impossible to eradicate.
Grain Mite, Flour Mite, Acarus Siro

Image a drawing found uncredited in many publications all over the web.
* The male of the species usually doesn't eat. It remains around the ovipositor, inseminating the females as they emerge. They develop the 4th pair of legs at maturity and claw like spines which enable them to hitchhike on other insects. They are also known to transmit fungi spores attached to their bodies.
Ah, how unfortunate, I was hoping I had some other kind of mite. What kind of predatory mite will control grain mites? The Neoseiulus californicus seemed to have fizzled out—I see lots of the grain mites and none of the N. californicus. I've had them for a couple years now and all my animals have been able to reproduce and be mostly healthy with them in the enclosures, so I'm not super worried about completely eradicating them, I just want to control their numbers and keep the terrarium ecosystem as balanced as it can be.
 

The Snark

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No idea what eats them. But, humidity below 50% or temperature below 50F and they (supposedly) quit breeding.
 

Galapoheros

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If they can move fast at all they aren't grain mites. It's a matter of what each person perceives as "fast" for what you're seeing and the pictures, like you said, not much a person can tell from those. If they are a uniform cream colored, white all over, then they are probably grain mites. If the they are brown--ish and move about kind of fast, likely to be some kind of pred mite. If they were grain mites, you'd have to stare at them for 2 or 3 seconds to see them travel a little bit. If you perceive movement easily, almost immediately, they aren't grain mites. They might be a good sps. to have. I just looked at your pics again, they look too dark to be grain mites. However grain mites can appear dark if they've been eating something dark in color. For example if they've been eating carrot, they will look orange, they're pretty translucent.
 

tzpnm

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If they can move fast at all they aren't grain mites. It's a matter of what each person perceives as "fast" for what you're seeing and the pictures, like you said, not much a person can tell from those. If they are a uniform cream colored, white all over, then they are probably grain mites. If the they are brown--ish and move about kind of fast, likely to be some kind of pred mite. If they were grain mites, you'd have to stare at them for 2 or 3 seconds to see them travel a little bit. If you perceive movement easily, almost immediately, they aren't grain mites. They might be a good sps. to have. I just looked at your pics again, they look too dark to be grain mites. However grain mites can appear dark if they've been eating something dark in color. For example if they've been eating carrot, they will look orange, they're pretty translucent.
Hmm, they’re much faster than that. I’ll try and get a better picture later, but it might take me a bit because I don’t have a good enough camera. Their heads and mouthparts are a reddish cream color, whereas their abdomens are a lighter off white.

They are maybe 1/3-1/2 the size of the big tropical springtails that are usually sold as cleaners, and they move fast enough and are large enough that it’s easy to see their legs, at least up close.

EDIT: Not sure what their diet is exacty, the only foods I can think of in the bin I took those pictures of is corn meal, rotting leaves and wood, dead isopods and roaches, fungus, and bacteria.
 

tzpnm

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Sorry for necroing this thread, but I took some better pictures of the mites. One is of the weird, cream colored mite with the red head and longish mouthparts, the other is of a mite I accidentally discovered in cage while I was taking macro pictures of the mites, I've never seen one like it before. It's small, rotund, and it's a deep red color. The white one moves pretty quickly. I recently had an outbreak of mites on another isopod bin that were very small and slow, matching the description of grain mites more closely. I quarantined that bin, and now it seems that those mites are much lower in number, but I'm still not sure what these faster, larger, cream/off white mites are.
image0.png-2.jpeg image0.png.jpeg

EDIT: I'll take more, higher quality pictures later, I'm still getting the hang of photographing these little guys.
 

boina

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I'm not sure what these mites are either, but it doesn't matter one bit anyway. The way they outcompeted and eradicated your springtail population they are almost certainly generalist predatory mites that will also prey on springtails. Fitting this is also your observation that you don't see them on your roaches. Fighting generalist predatory mites with generalist predatory mites is not going to be all that successful either. You'll just have a mite war and the species with more individuals usually wins...

So you likely have a predatory mite population in your enclosures. Since they only eat stuff that's they can subdue they won't do harm. I'd rather wonder about what they are eating - I mean they need to live off something living in there, too. They may possibly have lived off the springtails first and then off the grain mite populations that you find everywhere and they may be the reason the grain mite population you found is now reduced - prey/predator circle. Btw., there are quite a few red/reddish mite species of all kinds.

I just wouldn't worry. Grain mites are harmless enough, if a nuisance sometimes, and predatory mites are harmless, too. You introduced a predatory mite species yourself. Just let them be. If they get too many I just wipe them off and let the enclosures dry out a bit. Grain mites can survive in dry environments but for a population exposion they need moisture.
 

StampFan

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I'm not sure what these mites are either, but it doesn't matter one bit anyway. The way they outcompeted and eradicated your springtail population they are almost certainly generalist predatory mites that will also prey on springtails. Fitting this is also your observation that you don't see them on your roaches. Fighting generalist predatory mites with generalist predatory mites is not going to be all that successful either. You'll just have a mite war and the species with more individuals usually wins...

So you likely have a predatory mite population in your enclosures. Since they only eat stuff that's they can subdue they won't do harm. I'd rather wonder about what they are eating - I mean they need to live off something living in there, too. They may possibly have lived off the springtails first and then off the grain mite populations that you find everywhere and they may be the reason the grain mite population you found is now reduced - prey/predator circle. Btw., there are quite a few red/reddish mite species of all kinds.

I just wouldn't worry. Grain mites are harmless enough, if a nuisance sometimes, and predatory mites are harmless, too. You introduced a predatory mite species yourself. Just let them be. If they get too many I just wipe them off and let the enclosures dry out a bit. Grain mites can survive in dry environments but for a population exposion they need moisture.
Would you go to the extent that a grain mite in a T enclosure is a positive, harmless clean-up crew just like a springtail?
 

The Snark

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Would you go to the extent that a grain mite in a T enclosure is a positive, harmless clean-up crew just like a springtail?
As I read it, grain mites pose the problem of being abundant food for more aggressive predators. A built in food bank.
 

boina

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Would you go to the extent that a grain mite in a T enclosure is a positive, harmless clean-up crew just like a springtail?
Generally yes. There is the problem, however, that their numbers might get out of control. I've never had that happen with my tarantulas but I had a mite explosion in my feeder boxes on occasion because of all the food in there.
 

Chris LXXIX

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Summoning @boina, Our Lady of Mites.
Cora, Our Lady of Mites and Mold! :pompous:

@boina A 'Cake' rating, finally! Thank you my friend! :kiss:

Now I'm seeking for a 'Cookie' rating for gain 10 'Cookie' ratings :playful:

Happy New Year, my friend, btw -- Well, let's hope, at least
 
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The Snark

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Simple solution. Find feeders that don't mind temperatures below 50 F, the temperature grain mites stop breeding at. Then all you have to do is maintain that temperature for the lifespan of the grain mites. I didn't say it was a perfect solution. o_O
Around here the grain mite population balloons into the gazillions during the hot season and the rice crops coming in then drops to almost zero during the cold season.
 
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boina

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@boina A 'Cake' rating, finally! Thank you my friend! :kiss:

Now I'm seeking for a 'Cookie' rating for gain 10 'Cookie' ratings :playful:

Happy New Year, my friend, btw -- Well, let's hope, at least
And Happy New Year to you! - One more hour to go... ( sorry I'm slightly drunk :wacky:)
 

tzpnm

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Thanks for the help guys!

I went looking on google images, and the mites I have remind me of Stratiolaelaps sp. In terms of what they're eating without prey, I see them swarm over fish flakes and mold. I read that they eat springtails and fungus gnat larvae, so they could be hunting for those as well. The mite numbers in my isopod and roach bins has reduced, but they've now invaded my centipede cage and have out-competed/predated the fungus gnats in that enclosure.
(reportedly Stratiolaelaps scimitus--do you guys think it looks similar to the ones I have?)
 

StampFan

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Thanks for the help guys!

I went looking on google images, and the mites I have remind me of Stratiolaelaps sp. In terms of what they're eating without prey, I see them swarm over fish flakes and mold. I read that they eat springtails and fungus gnat larvae, so they could be hunting for those as well. The mite numbers in my isopod and roach bins has reduced, but they've now invaded my centipede cage and have out-competed/predated the fungus gnats in that enclosure.
(reportedly Stratiolaelaps scimitus--do you guys think it looks similar to the ones I have?)
Your post touches on one of the things I've been thinking about.

I keep reading "put isopods in an enclosure as a cleaning crew". But the grain mites are ever-present in my isopod enclosures (as well as my moist centipede enclosures) as they are the ultimate cleaning crew; my isopods are quite picky, won't eat a lot of the stuff that's fed, but the grain mites sure do....I find my isopods don't touch decaying feeder insect matter, mold, or fruit. The grain mites savour all of it....
 
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