Unfortunately, it's not as simple as that. Pesticides are poisons, otherwise they wouldn't work. Like any poison around the home, pesticides should be used as a last resort and with extreme caution. On the small scale of yards and family gardens, nonchemical pest control can be a feasible alternative.
Pesticides are toxic to many forms of life in addition to the species to be controlled.
Honeybees and useful predatory insects such as ladybugs can be killed outright when the pesticide is applied. Pesticide residues can accumulate in the food chain, causing damage to birds, fish, and other forms of animal life. Ultimately some side effects may extend to human life as well. Using a pesticide can be compared to taking a prescription drug, in that the benefits must be weighed against the side effects. In fact, extensive use of pesticides in agriculture has led to the development of genetically resistant insect and weed species that are no longer affected by some commonly used pesticides.