Pesticides are usually chemicals (organic or no) that are designed to interrupt the normal lifecycle of its target species. When pesticides are sprayed on foliage or the ground they kill not only the target “pest” but all other insects it contacts including the beneficial ones who perform necessary services like pollination, feeding baby birds, and controlling the targeted pest species. Killing beneficial invertebrates (dragon flies, native bees, ants and wasps, spiders, centipedes) whose role is to control other invertebrates, can cause the collapse of the predator-prey cycle and actually increase numbers of the undesirable pests which prompts application of more pesticides.
“To keep every cog and wheel is the first precaution of intelligent tinking” cautioned Aldo Leopold, father of wildlife ecology. Unintelligent Tinkering would be hiring a Mosquito Squad contractor to come out to your property to spray a pesticide (organic or no) that kills all the insects and leaves behind an ecosystem in collapse because the food source for birds and other creatures has been removed. All living organisms in nature have a role in the order of an ecosystem. If we remove a species or whole class of species by killing it off with a general pesticide we are only guessing at what the results of it’s loss will be.