How can I control pests outdoors?

Purchasing predators isn't a bad idea, but often they fly to the vacant lot next-door where all the good bugs are, leavng all the other bugs back home. Organic pesticides like neem-oil and pyrethrum are very effective but possibly mutagenic, so are best used as a last resort. Get a 20 gallon hose-end sprayer, IOW when twenty gallons of water have gone through the hose, the sprayer-cup will be empty.

Into the cup put:

1/4 cup lemon dish soap, but not a strong one like dawn
1 cup lemon ammonia, bugs don't like the lemon, and the NH4 is a foliar feed
3 T hot sauce (mmm...habenero)
1/2 cup tobacco juice

Go easy at first, its strong stuff. Wear gloves so you don't OD on nicotine. Oh, and don't use it right before harvest. If you have too many slugs for the old beer-can trick, sprinkle a mixture of pelletized lime and AlSO4 around where they go.
Spider mites can be controlled but not eliminated by spraying with corn starch and water. T he starch dries and suffocates them. Diatomaceous earth also kills invertebrates.