Get rid of pesticide resistant Spider Mites?

Question

I regretfully come posting asking for advice on how to get rid of a very tenacious spider mite infestation in one room of my indoor plants. I have become convinced these pests have become pesticide resistant because they have shrugged off neem oil, tobacco water, Sevin (Carbaryl), Malathion (a very strong organophosphate pesticide), Doktor Doom (pyrethrin, both the fogger and the spray), and something that came highly recommended called Wipeout.

Each attempt was whole-hearted, with me applying the pesticide at least 4 times liberally on the undersides of the leaves, spaced 3 days apart to get rid of the newly hatched eggs. Each time I see improvement for about a week before the leaves start getting sucked dry at an even more accelerated rate. I have also tried dusting with diatomaceous earth, and wiping down the affected leaves, all to no avail.

I am certain it is spider mites and not some nutritional deficiency because their webs are noticeable, I can see the wretched creatures when I inspect the leaves with a high powered magnifying glass, and its affecting multiple species of plant. Unfortunately heavy spraying with water is a non-viable option as the plants (mainly plumeria species) will suffer root rot if given too much water. I really do not want to have to discard these plants because they are fairly mature and rather unique varieties.

Is there anything on earth that will kill these vile pests without destroying my plumerias? As you can see I am willing to use just about any chemical at this point, but I am open to just about any suggestion. Your help is much appreciated.

[UPDATE] I tried both of Shule's suggestions of wiping down the leaves with rubbing alcohol and I spent some money on the predatory mites recommended. Rubbing alcohol didn't seem to damage the leaves terribly, and was very effective on the large broad leaves of the plumeria where it was fairly easy to wipe evenly. None of the leaves I wiped down suffered any additional damage. It was less effective on my ornamental peas where the small leaves made it difficult and tedious to wipe all the leaves. So I spent $60 on some Phytoseiulus persimilis mites. I hope they become established and permanently rid my plants of the irritating spider mites. I guess the moral of the story is don't use pesticides against spider mites. Thank you everyone for helping save my plants.

Answer 1

Predatory mites that eat spider mites might help. You can buy them, but they may be expensive. Make sure to remove any substances left on the plants that might kill the predatory mites.

We have a similar problem. This may not be an option for you, but I decided just not to start my garden plants indoors because of the spider mites. They didn't seem to be a problem started in the unheated greenhouse while they were there, except on a few ground cherries that I left in there too long.

I think all our apple trees and rose bushes attracted the spider mites, and they made their way indoors somehow. I think they'll be less of a problem if we remove the trees.

I haven't found anything that I've actually used that gets rid of spider mites. I haven't tried predatory mites, though.

I've heard that rubbing alcohol might be effective (I'm not sure about the eggs). I'm not sure if that would damage your plants. I haven't tried it. This makes me wonder if anti-lice shampoo would work, and if it would be safe. Probably not.

I think the spider mites hang out in the soil, too (not just on the leaves and stems). I've seen webs going to and from the soil (so that's my rationale). They also seem to hang out on plants they don't damage (so they can help to reinfect other plants). So, if you missed them in the soil or neighboring healthy plants when you tried neem oil, maybe try it again, covering the soil and the plant, and all the other plants. Neem oil is supposed to stop them from knowing they need to eat, drink and breed. I don't know that it kills them outright. Maybe a combination of that with a miticide at the same time would help.

Predatory mites sounds potentially a lot easier than other options, though. I'm guessing they may need a water source like ladybugs do to keep them alive.

Ladybugs don't seem to eliminate spider mites, by the way (even indoors; yes, we had some indoors once, with infected plants--not loads of them, though).

Sorry I wasn't more help. I'm interested in the answers you get, too.

Answer 2

Spider mites like warm, dry conditions and will thrive in such an environment, so it sounds as if that's what you've provided them with. Plumeria species like to be kept evenly moist from spring through summer, with significantly reduced watering in winter when they're dormant. They also like moderate air humidity - humidity and a plant that's well watered means spider mites don't like the conditions so much. You've mentioned Plumeria, but haven't said what your other plants are, so as far as the Plumeria are concerned, you could use pebble trays half filled with water to stand the plants on to increase humidity around them. More info here

http://www.guide-to-houseplants.com/plumeria-care.html

As for chemical treatments, the latest recommendation is to use a specific miticide spray rather than general insecticides, so you could try that. There's one on Amazon in the States called Mantis, but I can't speak for its efficacy. You might be interested to read the link below - it speaks of spider mite outdoors, but says there is evidence to suggest that some insecticides actually increase spider mite population, although quite why is anybody's guess, other than the assumption that insecticides are indiscriminate and kill other insects which may prey on the mites. Sevin, pyrethroids and some organo phosphates are mentioned as having this effect, so you might have been unwittingly exacerbating the problem.

http://columbustelegram.com/news/local/use-caution-with-insecticides-to-control-spider-mites/article_b6213642-a087-5be6-9b3f-96def4881f42.html

Answer 3

It makes me crazy to read that you may use pesticide inside... I re-read your question and saw it was a plant garden. Never mind. Be careful with pesticide.

One thing you could try is to use Diatomaceous Earth. This will arm any insect or arthropods because its so thin that it goes inside their joins and break them down.

Plus, it is not a chemical you can't use in organic gardens: its a natural occurring type of soil, with no known health impact.