I'm trying to remember the title of a book I read perhaps in 2010 or 2011. The book was a used paperback at the time, and might have been published in the naughts or the nineties. The cover of the copy I had showed some sort of slug creature that was very reminiscent of the Ohm from Nausicaä and the Valley of the Wind. It was a small, thick paperback like most other sci-fi shlock.
The book opened with two soldiers arguing about whether they were on a forest planet looking up at its forest moon, or on a forest moon looking up at its forest planet. An answer is given to them by a passing scientist. The general plot of the book, at least in the portion that I read, was the conflict between humans and a group of aliens that resembled robotic slugs, and maybe some insects or arachnids or something. The robotic slugs were prone to torturing captured humans and press-ganging them with mind-controlling chips, sort of like the Borg.
I'm sorry that this question is so vague, but I can't remember even the name of the main character. It's been bugging me (heh) for six or seven years now. Thank you in advance.