# Spider Mites?



## Draikan (Oct 23, 2015)

I have a sunroom in my house that has a mite problem. It's infested and they are killing some of the plants. I'm not able to spray off the leaves or use chemicals in that room, so I'd like to release predatory spider mites to hunt the plant eating mites. I'm looking at this product:

https://www.amazon.com/gp/product/B00HI2V7M8/ref=ox_sc_act_title_3?ie=UTF8&psc=1&smid=A1WMQPAGZ5642Q

I'm worried that these same predatory spider mites might be the same kind that can infest a viv or FF culture. The sunroom and my terrarium stuff are at opposite ends of the house. Should I be worried about contaminating from the sunroom to the terrarium or FF cultures? Has anyone used predatory mites to treat plant pest mites before?


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## kimcmich (Jan 17, 2016)

Draiken,

Spider mites are a major pain for indoor horticulture of all kinds. They are also very hard to eradicate by any method and even harder to get rid of permanently if your conditions (or chosen plants) encourage them.

Mites (and plant-sucking insects more generally) thrive in low-humidity because they rely partially on evaporation to move their liquid food and wastes through their bodies. This is also a reason why spider mites are rarely a problem for outdoor plants in humid climates. Increasing the humidity in your sunroom might help.

You should also observe what kinds of plants seem immune to the spider mites. These are likely the kinds of plants you should favor in your sunroom over the ones hardest hit. Sadly, anything with a major infestation is likely a lost cause (and a source of re-infection later) and should be discarded or moved outside at the least. 

I find some plants that attract spider mites like a magnet when grown indoors will recover almost immediately when moved to grow on a porch (and getting hosed off or rained-on).


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## Entomologist210 (Apr 24, 2014)

_Phytoseiulus persimilis_ only eat _Tetranychus spp._ and should be safe to introduce. However, you might have to introduce them in big quantities to quickly overtake the spider mites.


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## Ed (Sep 19, 2004)

Raise the humidity, in addition to the predatory mites. Spider mites don't do as well under high humidity conditions. 

Some comments 

Ed


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## Draikan (Oct 23, 2015)

The sunroom has a pond, and dehumidifier to control the humidity. The pond evaporates and the dehumidifier returns the moisture to the pond. The room is controlled to 70%, and has decent circulation from a ceiling fan. I'm not comfortable raising the humidity any further since this is an indoor space. It's the colocasia and Alocasias that have the most trouble with mites, probably because they have the fleshier leaves. My ferns seem unaffected.

I can't really rotate the plants outside, some of them are too big and heavy. I don't think I need to wipe out the mites entirely, I just need a predator to keep them in check. I'm mostly curious whether the predatory notes could be a risk to the terrarium on the other end of the house. I'm leaning toward trying it, especially since it sounds like the terrarium is too humid for mites anyway.


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## kimcmich (Jan 17, 2016)

I've found Alocasia to be spider mite prone myself. Even with predatory mites, you may find that plants like Alocasia still suffer. At 70% humidity you're already doing as much as you can there. Have you been growing the Alocasia long indoors before the spider mite problem?

To clarify, plant-sucking mites like lower humidity. Predatory mites are a different matter - though I think entomologist is right that the mites you want to use should not be a problem for your terrariums.

Spider mites are also very sensitive to soap treatment. Just a mixture of soap and water sprayed on the leaves will kill many of the mites - this would be a good pre-treatment before you introduce the predatory mites.


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## Draikan (Oct 23, 2015)

I had the alocasias doing fine for months. As soon as the mites turned up they started going downhill. I think they came in on one of the plants I added.


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## Entomologist210 (Apr 24, 2014)

I think adding a large number of _Phytoseiulus persimilis_ will help with the problem. What plants did you add that you suspect caused the infestation? Most Tetranychidae have a limited host range (with some notable exceptions), so have you noticed any plants that seem totally free of mites? Where is the infestation concentrated? Upper -side of leaves? Under-side? Kind of moot really since the predatory mites (if supplied in sufficient quantities) are likely wipe out the issue. I'm just curious since I study mites. This should basically be like "Huffaker's experiment" without the avenues for escape.


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## Tricolor (Jun 12, 2009)

Would ladybugs eat mites? I know they sell them in seed catalogs.


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## Draikan (Oct 23, 2015)

I searched around for ladybugs and got mixed answers about their mite effectiveness.

I think the mites originated on one of the Alocasia I got from Home Depot.

My ferns, spider plant, pothos, wandering jew, tillandsias, and begonia are unaffected. Orchids are so-so. Alocasia, Colocasia, and celosia are really bad. The plants are in a roughly 13'x15' room only a few feet between them. Even if the mites can't travel around I probably distribute them when I move about in the room.


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## Draikan (Oct 23, 2015)

Thanks for mentioning Huffaker's experiment. The Wikipedia article is interesting, and linked below.

https://en.wikipedia.org/wiki/Huffaker's_mite_experiment


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