The hot, dry weather makes life better for spider mites because it makes them suck out more plant juices which acts as an aphrodisiac so more spider mites are produced. This hot, dry weather also causes the predators of spider mites to stop working. The simplest means of control is to do what you can to increase the humidity of the affected plants which will slow down reproduction and allow the predators to get back to work. Insecticidal soaps also help control these buggers.

Here is a link that might be useful: About spider mites

I really don't think I can make it more humid here in Saint Louis. When I said dry I meant we had not had rain in weeks and we are short on rain overall for the year, I guess I wasn't clear...:)
Our average humidity in St.Louis during the summer runs about 50% with peaks in to the 70% ranges on hotter days. My garden is multiple raised beds and rows of pots in different places in the yard for a total of about 600 square feet of raised beds and 60+ pots. I am already at 50% humidity on most days due to the weather
I thank you for the link and it contains an excellent pic of the little buggers.

1. I don't know how to raise the humidity overall in my backyard or that I even can. We water with soaker hoses and while I can spray down other veggies I can't directly spray the foliage on the tomatoes with water or I encourage the fungal and soil born diseases to take hold.
2. I have tried insecticidal soaps, pyrethrin-rotenone, neem and in a case of past desperation have resorted to even more toxic chemicals. I don;t want to use those since they kill everything including all the ladybugs, lacewings, praying mantis, bees etc that I have acquired over the last few years, but I don't think I have a choice if the parasitic mites don't work.
thanks
kendra

I have had this problem too, on my watermelons. I found that the insecticidal soaps (like Safer) can work well if applied early on before the infestation becomes too severe.

I also found that by regular watering down of the surrounding soil and the plants themselves I can delay the onset of these guys.

Wayne

Increase the humidity of the plants by misting them several times each day.

thanks everyone for your help, I guess I just need to be more diligent with the spider mites and attack early...:)

Basically though what I am understandng is unless I can raise humidity around my plants directly, the predatory mites etc are not going to be helpful?

kendra

try Superfine oil which is a parafin wax. this is a miticide spray. it coats the mite and it dies when the wax dries on the mite.

I find a lot of fresh air helps. stagnant air breeds mites. a nice windy spot stays clear of mites. I will bet you have stagnant air. give good room between plants for the air to flow.

I never spray poisons so there are tons of preditors around. lady bugs everywhere.

You might grow some buckwheat it attracts all kinds of bugs umbelieveable good once it starts to flower and keeps going.