The Green Brain, Frank Herbert's 1966 book is credited with being one of the first eco - conscious novels.  In an overpopulated future earth the contrarily named International Ecological Organisation has to clear the jungle and exterminate vicious insect life of the Mato Grosso for living space.  The insects rebel against the hi tech destruction rained on them, which has the power to ruin life for the whole planet.  Under intense selection pressure the insects are forced to evolve, forming a new intelligent life form with a conscientiousness of it's own, able to hunt even as it is hunted.  There are huge mutants, some of them mere insects, but some more man than insect.  Fairly simple in style, not vintage Herbert, but an exploratory work which tackles themes that reappear in his more powerful 'The Dosadi Experiment'