Mites(??) in substrate

[Predatorhousepet]

I was cleaning out my mantis's deli cups and noticed these small white insects all over the discarded carcass of a bluebottle fly. I think they might be mites but I am not sure. Does anyone know what these are and if they are potentially harmful to my mantis?

 I found more of these bugs in the substrate of a second deli cup (2 out of 5) but they don't seem to be present in my fruit fly, springtail, or isopod cultures, or the planted terrariums where the older mantids live and the holding pens where I keep hatched flies don't seem to have them either so I am unsure where they came from. I threw away the substrate from both cups and moved the inhabitants to brand new ones. If these are mites what else can I do to keep them from coming back? Would diatomaceous earth sprinkled underneath the cups help or are they coming from the flies? If the flies are infested are they bad to feed to my mantises?

For scale, that is a 1oz cup lid with a partial bb fly carcass and 2 of the "mites" circled.

 

[CosbyArt]

@Predatorhousepet Doesn't look like any form of mites, but some larvae or eggs. As you are using flies for feeders those could be newly hatched fly larvae.

Did you record a video before disposing of them? I ask as their movement could help in a proper ID of them. You did not mention if they moved or not, and mites are always on the move. Mites have legs and have vastly different mobility compared to larvae that crawl - I say that as in none of the photos is any sort of leg visible (and appear moist with reflections on their bodies which again points to eggs or larvae).

For photos and a video of mites see below...

 

[Predatorhousepet]

Yes, they have legs and they move. The last closeup pic I posted shows the legs and the front of one. I did make several videos of them, I will post a link shortly, just need to upload them somewhere.

 

[Predatorhousepet]

I have three short videos uploaded and linked below. (Sorry they were shot in portrait mode. I was using a 10x macro lens + digital zoom and the lens is quite heavy so it's hard to hold my phone still when it's horizontal and zoomed in that much.)

https://youtu.be/NWOm_YNk76o

https://youtu.be/aWERTne02gw

https://youtu.be/G5Yf9itrdxo

 

[Predatorhousepet]

After looking at the pics and video you posted of actual mites, I agree these do not look the same. They seem to move slower and have large dome shaped bodies and a tapered head. They weren't very many that I could see, maybe 20 at most, of various sizes. They might have been feeding on the fly's corpse since that is where they were mostly concentrated. They could be some sort of clean up insect but I wasn't sure and I feared they could be mites so I just disposed of them.

 

[CosbyArt]

@Predatorhousepet The videos confirm it is a mite after all. After digging around online it appears to possibly be Acarus siro, compare the photo here to what you have.

The mite prefers moist substrate, and "These mites live in various habitats (including bee nests), where they feed on decomposing organic matter and fungi." (link see last photo). Here is another source too, with a photo that is not a microscope lit view making them appear transparent.

While they should not bother your mantids (see here) they are a nuisance and can spread to other things where they can compete for food (fruit flies, springtails, etc) where they would be a concern. They can be easily transferred by walking the distance themselves, hitching a ride on a breeze - or your hand, and will undoubtedly find their way to other containers. Yes, in this instance they are acting as a cleaning crew but is one that you don't want.

If these are mites what else can I do to keep them from coming back? Would diatomaceous earth sprinkled underneath the cups help or are they coming from the flies? If the flies are infested are they bad to feed to my mantises?

To keep them at bay you can try the mite paper product (Mantisplace link). Also depending on the mantid species, keeping the habitat humidity below 55% RH will cause them to die off (link here). Personally I find changing substrate and cleaning habitats are typically enough to remove them, and the lower humidity (at least for awhile) will kill off any remaining.

The diatomaceous earth would be something to avoid, if any ends up inside the habitat it will hurt and/or kill your mantid as well. That is if your hand touches the habitat bottom and picks up any DE (when you remove the lid or move the habitat) it can easily fall inside the habitat, or contact anything else you touch afterwards. For that matter even a small gust of air from breathing nearby may direct DE into the habitat. "Diatomaceous earth causes insects to dry out and die by absorbing the oils and fats from the cuticle of the insect's exoskeleton. Its sharp edges are abrasive, speeding up the process." (link)

If the flies are infested you can feed them to the mantises, again they are a nuisance (especially in numbers) but will not harm them.

I've had fruit fly cultures that were highly infested, but had no choice until I was able to buy new cultures due to the small instars. The mantis nymphs would groom more often to remove the mites and looked awful to see them crawling on them. Of course when I held the FF cultures to get flies out they also traveled up my hand and within minutes would be on my head - they cause itching for hours, but washing hands/arms/face with soapy water (or taking a shower/bath afterwards) kills them off.

Ideally you will need to replace any mite infested cultures, and sources, with feeders that are mite free; otherwise, mites will continue to be a problem.

 

[Predatorhousepet]

Thank you for identifying them. After disposing of the mites I haven't seen them anywhere else so far. Your link says they are often found in cereal products, the only cereal I have anywhere near them is the Gerber baby oatmeal I use to make food for my springtail culture and the dry fruit fly media mix I bought from Josh's Frogs. I doubt either of these are infested, however, as I store them in a mini fridge in my room. The bluebottle flies come from pupa also stored in the fridge. After they hatch I put them in a deli cup, where they are held until I need them. I was putting coconut fiber substrate in their cups but since these mites like moist substrates I will stop doing that and just use dry paper towels in the bottom instead. I haven't actually seen these mites in with the flies but I might as well take some preventative measures. The infestation you were describing sounds absolutely horrific, it makes me uncomfortable just to imagine it happening. I only found around 20 total mites and that was too many for me. I was already replacing the nymph's substrate once a week but I will increase it to 2 or 3 times a week.

Edit: I'll stay away from the DE. I was mainly asking about it because that is the main ingredient in the mite powder Josh's Frogs sells as part of their fruit fly culture kit. The instructions say to sprinkle it underneath the fruit fly culture cups to keep mites from getting in. I hadn't had any issues with mites up until now so I didn't see any need for it previously but you bring up some excellent points about accidental transfer. I hadn't considered that could be a problem. DE is a particularly awful way for an insect to die, natural or not, and I wouldn't want my mantises to meet their end like that. Better to just clean out their substrate more often than to risk it.

 

[Predatorhousepet]

I've been keeping an eye on the substrate to make sure the mites don't come back and noticed there is a layer of fine mold or fungus growing on it instead. I just changed the substrate yesterday, why would that be happening so quickly? I keep the substrate slightly moist but not damp or dripping wet. Looks like I might have to change the mantis's substrate to something else too. I don't really want to use paper towels, any other suggestions that would discourage both mites and mold while maintaining humidity?

 

[CosbyArt]

After disposing of the mites I haven't seen them anywhere else so far.

That is good to hear, and hopefully they will be eradicated.

I'll stay away from the DE

One trick besides the mite paper mentioned is to keep your cultures in pans of shallow water. While most do it for fruit fly cultures (which can develop mite problems especially near the end of their cycle) it can work for small nymph containers. The only real problems with the pan of shallow water is it needs to be shallow enough that the containers don't go floating off, it must constantly be maintained with water, and can be mess or electric danger if spilled.

I just changed the substrate yesterday, why would that be happening so quickly? I keep the substrate slightly moist but not damp or dripping wet

I saw your other thread and responded there.

Regarding dampness that is one aspect no one tends to agree on in color/look wise. Speaking in terms of humidity (found on a hygrometer as RH % (room humidity)) is best and much more accurate, and takes air flow and other variables into it's percentage.

For example dry coconut is a light tan golden color, damp it appears tan (and starts to clump/ball up), light brown is moist (and if clumped will hold it's shape), and brown or darker range is excessively wet (and if clumped will drip water). Put simply, the coconut absorbs water, so if any moisture is visible then the coconut is too damp for mantid humidity needs (except high air flow habitats or extreme humidity needs).

Again though a hygrometer removes all the variables and shows a accurate measurement of the humidity.