The Dragon Queen of Jupiter by Leigh Douglass Brackett audiobook.
The French Foreign legion has been exported to Space as the Space foreign legion. They are fighting now on Jupiter and the natives, led by their Dragon Queen, are winning. Earth and Mars need places for people to live and grow food but Jupiter may be too hard a nut to crack. Will the Legion be able to hold off the hordes Beetle Bombs and venomous snakes until a relief column arrives? Or will they die in horrible pain like most of them already have? And then the Dragon Queen uses the ultimate weapon, a parasite that stops them from drinking any water.