A Season for Slaughter by David Gerrold (The War Against the Chtorr #4)

From the author of the Star Trek novel, Encounter at Far Point comes the fourth book in his riveting epic of alien invasion and conquest. Only luck, sheer will and an incredible ability to adapt will bring the expedition to safety, when a Special Forces commando and a scientist lead a group of experts into the heart of the alien invasion in South America.

Paperback, 1992 Goodreads: 4.08