What are the ""agencies"" to which Rachel Carson refers (para. 33) ? Why are they reduced to ""so-called control agencies""?

The agencies being referred in Rachel Carson's "Silent Spring" are the state and federal agencies.

They are being reduced to the "so-called control agencies" because they don't really know much about the effects of chemical insecticides and how potentially dangerous they are to living things, yet they are the ones who allow its distribution to people. They control the insects in the world by allowing spraying operations, however they don't have any idea on how much damage they are causing to the world. Carson reduced this agencies because they were spreading "misinformation."

Explanation:

"Silent Spring" was a book that stirred the public's attention. It talks about the bad effects of using chemical pesticides to the environment. Many critics opposed the book, yet it was able to move the Congress. This resulted to the operation of the Environmental Protection Agency in 1970.