Here is an article I just read that looks interesting - comments will be appreciated. I plan on trying this on one of lemons. It was used on a hibiscus plant. The website I found it at is www.hiddenvalleyhibiscus.com.

DROWNING SPIDER MITES

This is our favorite method for all hibiscus growing in small-medium pots and for houseplant hibiscus. You only have to do it ONCE to kill all spider mites and their eggs. It kills every kind of spider mite, even the most microscopic ones that can hide in cracks in the bark. This method does require precision and care. You'll need a timer and a thermometer - a kitchen "candy" thermometer is perfect. If the water is too hot or you leave the plants too long, you can damage the leaves and they will all fall off after treatment. If the water is much too hot and you leave the plants much too long, you could actually kill a very young plant. But if the water is too cool or if you don't leave the plants in the water long enough, you won't dissolve the covers of the eggs and kill the growing larvae, which means the infestation will come right back.


A Large Sock on a Small Pot

Wrap the hibiscus plant pots in some kind of fabric and use a twist tie to secure the fabric around the base of the plant. The fabric must let water through, so don't use plastic bags, or you will carefully protect any pests that are living inside the pot and soil. Large socks or pantyhose work well to wrap up small pots, and pillow cases work well for large pots.
Lay several hibiscus plants on their sides, pots and all, in a bathtub. You can put many of them close together in a single layer in the bottom of the tub.
Fill the tub with water that is bathwater temperature - about 90°F (32°C). It should not be so hot that you can't comfortably keep your skin in it. What feels too hot to skin will risk damaging your plants' leaves.
Fill the tub until all the plants are covered, and weight the plants down to make sure all parts of all plants are submerged in the water. (An easy way to weight them is to cover the plants with two large towels, then to pull the two shelf racks out of your oven and lay those carefully over the top of the towels.)
Leave the plants submerged in the water for 45-60 minutes.
Drain out the water and stand the plants up in the tub until the excess water drains out of the pots.
Remove the fabric covers, and scoop any loose soil in the fabric back into the plant pots.
Leave the plants out of bright light for a few hours to rest, then put them back where they belong. Be careful not to water the plants again until the soil dries out after this thorough soaking.

Unless plants are recontaminated by exposure to another infected plant, plants should remain free of spider mites, aphids, and other pests for 4-6 months or more. This method has the added advantage of leaching out any build-up of fertilizer salts in potted plants, which needs to be done once or twice a year. So it is two plant-care activities in one.

Seems like a mess and a lot of trouble. Actually, spider mites and their eggs are very easy to kill, just with a spray of a horticultural oil (HO). Never spray during the heat of the day, spray in the evening. Horticultural oils are totally non-toxic to humans and animals, and qualify for use in organic programs. HO will also eradicate mealy bug, aphids, scale, powdery mildew, alternaria and whiteflies. - Millet (358-ABO-)

I've also had pretty good luck using predator mites as well.

Every year when I take my citrus inside, I battle spider mites and soil gnats, I would usually spray 2 to 4 times a winter. They love the humidity and mild temps it seems. This year I tried HO based on Millet's recommendation. I sprayed very thoroughly(top of leaves, underside leaves, stem/trunk, top of the soil lightly, containers and ground near them) in September. I have yet to see a spider mite or gnat - and I look for them. HO works.

I took my own advise and drown my trees/bugs. I have a large 50 gallon trash can and filled it up with water (cold tap water) from the outside spigot. It was a warm March day, took my Mandarin and placed a clothe over the pot and sank the tree totally under water for two hours.

The Mandarin has been giving me a hard time - not producing fruit so if it died I would not be heart broken. The water was to cold to keep your arms in it for more that 10 minutes. The Mandarin has survived and appears to not had any bad effects from the cold and water (I let is sit in the sun for several hours.) The interesting job was taking my 9 year old Eureka lemon which was to large to totally submerge, I turned it upside down with the pot outside of the trash can and submerged the tree for two hours in the same water, which was warmer now.

After two hours I turned the plant right side up and put the pot in the water for two hours. I don't know if I killed the bugs but I sure gave the a run for their money. I will have to wait until I get new leaves to really tell if I killed the bugs. Sorry there are no pictures, you would have gotten a good laugh at the tree upside down in the trash can.

I use lime sulphur spray twice a year. In late winter and again in the fall when the day time temp falls below 85 degrees F. have had excellent control using this method.

It has now been several months - the mandarin has just died, it never was very cooperative. The Eureka has added several new limbs and many leaves all without any bugs - leaves are shiny and happy, no new buds but hopefully soon! The judgement is that drowning your spider mites in a 50 gallon trash can in March in Denver is a good way to get rid of them for a while! Has anyone tried this idea yet? It is a bit far out there.

I use a product called mighty wash chen I had mites and webs all over my lemon tree, that was a few monthes ago and havent had them back since. Seems to have worked real good.

http://www.sunflowersupplies.com/products/MIGHTY-WASH-QUART-MITE-KILLER-%252d-USE-UP-TO-LAST-DAY!.html

I got it there and sprayed it on full strength and havent seen any webs since.

your link did not work to me.

I found it here :

http://www.sunflowersupplies.com/search.php?search_query=mighty+wash

Diatamatious Earth edible kills them .
wolfcreek has lots of info so do a google it works and is also not going to harm anything but the mites fleas and r bad bugs

wished I would get it here ...

I just use soft soap (Schmierseife).

What can be done if Neemazal doesn't help agaisnt spider mites anymore? There's a product here called "Vertimec", which main ingredient is Abamectin, do you know anything about how effective it is?

It is very effective.

I used an Abamectin product for several years. Initially it worked well, but my spider mites (the red citrus mite) became resistant. It was also very expensive.
I now use the Bayer product called 'Spint'. I always have a small hand sprayer with this in it, and spot treat any plant with mites. They are all dead the next morning.
Bayer Spint is not available in the UK but is sold online by several Dutch suppliers. It is also quite expensive, but it is sold in small quantities and you only need a tiny amount, so it will probably last for several years.
Mike/Citrange