Aphids can be the gardener's nemesis. They show up seemingly out of nowhere, breed quickly and feed by sucking the juice out of plants while excreting a damaging substance. Many gardeners use pesticides to get rid of these tiny annoyances, but pesticides also kill the best defenses against aphids: their predators.
You may not think of them as tools, but insects can be excellent garden gadgets. While pretty in their red and black, ladybugs are powerful green tools for getting rid of aphids since they'll feed on them quite aggressively. A ladybug can eat more than 5,000 aphids and other pests during its one year of life [source: Nature's Control]. Ladybugs and certain beetles will also eat your pesky mealy bugs, and predator mites help control other, unwanted mites, such as spider mites. And be kind to earthworms; they cause you no harm and help cultivate your garden. Sometimes the most powerful tools are the ones provided by nature!