Rather than starting out with some very toxic means of control try spraying with water. Spider mite populations grow when the weather gets hot and dry, and often just increasing the humidity around the plants helps.

Here is a link that might be useful: About Spider Mites

To be most effective, direct the harsh water spray to the undersides of the leaves.
Repeat every several days for a while.

one should read the LABEL ... to find out what plants to use any given chemical on ...

and one should start with the least intensive solution first ... as in spraying with water..

before contemplating full bore nuclear warfare ...

ken

A sharp spray of water can be helpful in knocking off the spider mites, but to get adequate control, raise the humidity around the plant, you would need to mist daily, or more often.

Misting plants is not an effective way to raise humidity, though some people still believe it to be true. Misting raises the humidity around the leaves for as long as the foliage remains wet. A few minutes, an hour? Then, whether in the great outdoors or inside the home, any imagined benefit....evaporates.

Frequent misting of outdoor or indoor plants can create an ideal environment for the development of certain diseases and the rapid spread of those diseases.

We have control over humidity levels in an enclosed environment, like a greenhouse, an enclosed atrium, or terrarium. I used to spray the floor and sides of my greenhouses to maintain a high humidity inside the whole house in the winter months when RH levels dropped, for example.

Spider mites can also thrive in a humid environment, as anyone with a greenhouse or outdoor garden can attest to. My garden and container plants support an active spider mite population all season long, even though the average humidity remains above 85%. High humidity does put a damper on the mite's breeding.

I keep them at acceptible numbers with an occasional spray to the underside of the leaves. Tomato plants, susceptible to both mites and whitefly, are sprayed with neem oil a couple of times during the season, if needed.

I have to agree with Rhizo. I live in a very humid environment and although it's been touted across the internet that spider mites don't like humidity, they still thrive in it. I have a fight with them 3 times a year, whether it's dry or wet/humid.

Spidermites are becoming immune to Avid, so if that doesn't work, try Forbid. With the Forbid, you don't have to re-spray in 3 days to get the eggs, nor do you have to hit every mite, it's systemic and travels through the leaf and kills them dead.

BTW, Avid is using the same chemical to kill the mites that kill fleas and ticks on your dogs. I had to move from Avid to Forbid,, and have been using it for about 4 years now, every 3 months to get rid of them. And it works.

I have never used tetrasan, so can offer no advie on it. I have used Avid and Forbid on hibiscus (as a spray) with good results. Just never use it as a soil drench, I did that once with drastic results, but the spray is fine.

Amazon sells Forbid in small amounts that are reasonably priced. And a little goes a long, long way.

Like the others offering advice to watch/read up on what you spray, I totally agree and try to stay as organic as possible. But spider mites are absolutely immune to almost everything. Just be careful how you use it, and make sure no beneficial insects are around when it is applied. I also grow many plants to intentionally attract butterflies, so I only spray when there is no breeze, and before the butterflies come out. It dries in a few hours and even rain will not stop it's potency after that.
(And I never spray butterfly plants with anything!)

edit: Lastly, Rhizo is right about the Neem. It will keep them away. But unless you are religious about applying it every 3 or 4 day, all spring and summer, they will find your plants, at least in my case. It works as a deterrent, not a 3-month cure. I have too many plants to go that direction,
busy life; so use the Forbid.

This post was edited by MsMorningSong on Tue, Jun 10, 14 at 17:41