Despite the best attempts of scientists to control insect populations by using chemicals, entomologists find that “problems they had considered solved a few years earlier [have] returned to plague them” (246). Not only are insects “developing strains resistant to chemicals,” but the use of these insecticides is “weakening the defenses inherent in the environment itself” (246). Through these disruptions to the “balance of nature” (246), humans are causing more harm to themselves than good.

Carson articulates that there are two core issues with this weakening of nature’s balance. The first is the balance between insect populations and “the resistance of the environment” (247) which keeps populations from spiraling out of control. The second is the “truly explosive power of a species to reproduce once the resistance of the environment has been weakened” (247). When predators are removed from a populations environment, for example, populations of prey are able to reproduce unchecked. Widespread spraying to control one population of insect often results in a weakening of the environment that can lead to that population returning in greater numbers.

The primary goal of chemical spraying is to reduce insect populations, yet “in many areas and among many species only the strong and fit remain to defy our efforts to control them” (263).