The 'in word' is green. Paper (recycled), non chemical pesticides, herbicides, and all those products that have the 'white arrow triangle' are considered GREEN and using them will reduce your carbon footprint on our planet. However, this GREEN movement comes at a high price, so I have decided to offer an alternative lower cost for organic pesticides that one can manufacture at home.
Numero Uno on the organic pesticides is garlic. Technically garlic is not a pesticide because it does not usually kill but repels many pests. These pests simply do not like the taste or smell. There are two methods for garlic application. One, you plant garlic around other plants and this would keep many pests off. For example, planted around tomatoes, it can prevent red spider mites. Incidentally, salt water spray is also effective for red spider mites. Garlic around fruit trees can repel borer beetles whose larvae would bore into your tree trunk, damaging or even killing the tree.
Secondly, an organic pest control spray from garlic blended with water or oil, sprayed directly on growing vegetables or flowers prevents rabbits and other invaders from snacking on your plants. Using an oil mixture and sprayed onto ponds or any collection of stagnant water will form a film on the surface of the water that can kill mosquitoes.
A common product found in most households until recent years is boric acid. One can still purchase it in drugstores or online. It is a natural product mined in the Mojave Desert. Boric acid has anti fungal properties that can be used to get rid of mildew and other molds and fungi. As a power it is very effective against ants, termites, ticks, fleas, bedbugs, slugs, earwigs, beetles, roaches and even scorpions. Not to forget, it will terminate crickets and grasshoppers.
A side note, boric acid is mildly toxic to humans or pets. It is not more dangerous that table salt. A pet would have to eat a lot to suffer symptoms and humans much more. Remember, it is not for internal use by humans and should not be used excessively on plants that pets will lick or eat.
Liquid detergent and others can be effectively sprayed onto roses and other plants that are infested with aphids or small fly infestations. Quite effective against slugs. For the old one two knockout punch add equal quantities of hot chili peppers, horseradish(roots and leaves), spearmint and green onion tops to your soap water.
I must state that most of the homemade organic pest control concoctions we use do not actually kill the insects or other pests; rather, prevent them from coming near your plants. The exception, boric acid which is truly a pesticide.
In keeping with the theme pest control, another aspect is companion planting where one plants certain vegetables and herbs the have protective qualities in the garden. There proximity to each other appears to fend off harmful pests. This phenomenon is particularly noticeable with food crops. Vegetables can be protected from the most damaging pest threats by planting them close to specific types of vegetables or herbs.
The keyword here is allelopathy.