Red Spider Mite fight continues

I have recently used The Provado Ultimate Bug Killer aerosol spray which has the active ingredients Methiocarb and Imidacloprid to control kill Red Spider Mites. First application was in early January and it seemed to work, (its hard to tell when the mites are smaller than pin heads). Yesterday I've found the leaves of my lovely brugmansia covered again in the bugs, the underside of the leaves look dusty and leaves are yellowing fast and dropping off. I have applied the Provado again today but, after reading lots of information on gardening forums everywhere I am fully expecting the bugs to now be immune.

According to the Royal Horticulture Society website,

"Chemical control

Insecticides containing bifenthrin (Bayer Sprayday Greenfly Killer Plus, Scotts Bug Clear Gun or Doff All-In-One Garden Pest Killer) will control red spider mite, provided it has not gained resistance to this substance. Bifenthrin can be used on some edible plants - see the label instructions. Alternatives are sprays containing thiamethoxam + abamectin (Westland Bug Attack Ready To Use), acetamiprid (Scotts Bug Clear Ultra Gun), which are for use on ornamental plants only. Edible plants can be sprayed with plant oils, plant extracts or fatty acids (see above). The latter pesticides may require more frequent applications."

So from this I gather that the chemicals bifenthrin and thiamethoxam + abamectin and acetamiprid are thought to effective. These should be alternated so immunity cannot be gained by the bugs. So my next move is to get some Bayer Sprayday Greenfly Killer Plus and Scotts Bug Clear Ultra Gun or Westland Bug Attack Ready To Use and alternate the two. If i only had a garden I dont think I would have this problem, I dont move home to a garden until july.

There is also the question of insecticidal soap. My only experience of this is the Spidermite Control, containing 1% Coriander Oil, 94% Canola Oil and 5% Triethanolamine. The instructions say to dilute 25ml of the solution with 1 litre (1.75 Pints) but last time this scorched the leaves of the plant and I lost a lot. Maybe I will reduce the strength of the mixture and leaf wash my plant next tuesday.

No doubt I will write more about my battle and what if anything works.