Spider Mites thrive in hot, dry environments, cool the area down and increase the humidity of the area and the populations will drop. Insecticidal soaps will help. too.

Adult Whiteflies can be trapped on yellow sticky traps and the larva in the soil can be easily dispatched with insecticidal soaps or garlic oil.

Here is a link that might be useful: Spider Mites

Ummm. Whitefly larvae are on the plant -- on the undersides of the leaves -- *not* in the soil.