I think organic pest control is one of the aspects of organic gardening that really lures people. Fighting pest insects with other insects or using some common household compounds to kill bugs really is appealing.
One of the awesome benefits of organic gardening is that you will grow healthy plants which will be able to resist pests. Just as wolves prey on the sick, weak and old; insect pests will attack sick, weak plants.
Natural Pesticides and Their Uses
The following work best on small, soft-bodied pests such as aphids or mealy bugs. The white, cottony dots in the picture below are mealy bugs.
Your first line of defense is blasting bugs off with the hose. If you see pests on your plants, try a hard stream of the hose to physically relocate them.
If the pests are resistant and need more convincing, you can spray them with soap spray. Just mix a few shavings of ivory bar soap or other natural bar soap with water in a spray bottle. Do not use dish detergent. Spray your pests regularly for a few days. They should dry up and disappear. You can also use insecticidal soap.
Diatomaceous earth is a similar strategy to the soap. It creates an unsafe environment for insect pests. Diatomaceous earth is the fossilized remains of algae, which has turned to rock. It causes insects to dehydrate and die.
Pyrethrums are a ground up flower which are poisonous to most insects.
Dormant oil is great for scale insects. The oil sticks to their bodies and suffocates them.
Tobacco if you are a smoker or know one, collect the butts. Soak the butts in water for several days. Put the water in a spray bottle and spray away. Tobacco contains harmful compounds which can kill insect pests.
With strategies like these, organic pest control is inexpensive.
Natural Pesticides Do Not Have to Be Compounds
Beneficial insects
If you see ladybugs or praying mantis in your garden, rejoice. You must be doing something right. These insects prey on harmful insects in your garden.
For outdoor gardening, you really do not need to purchase beneficial insects. I think these insects are best utilized in greenhouses, where you have a closed system.
I'd also like to mention that ants are not harmful to your garden. My brother killed some tomato plants because he was so freaked out by the ants crawling on the plants.
Beneficial birds
Evidently, grasshopper infestations can be controlled with domestic chickens or turkeys. I've also read that they will make short work of caterpillars, fleas and ticks as well. This makes sense. So if you've got an infestation, but no birds, maybe you could borrow some. Or buy some birds and sell them at the end of the growing season.
With birds, you'll get the extra perk of great fertilizer from their droppings.
This charming Aussie sums up the thinking below:
Beneficial reptiles
I worked for a couple who completely wiped out a snail infestation with a few tortoises from the pet store. Snails were everywhere including the sides of the house and windows. After the addition of 5 tortoises, the snails disappeared. The tortoises still live in their backyard and happily keep the snail population under control.
Organic pest control doesn't have to be a matter of spraying the right compound. Think in terms of the system. Healthy plants thrive in a balanced system. When you have a problem, ask yourself what's needed to balance the system?