Inside Jupiter - Inside Jupiter, #1

Walt, 14, and his sister Mindy, 12, are attacked by giant sword-bearing warrior butterflies in their first outing after crash landing inside Jupiter. The only survivors of their ship, they soon learn that all the remaining colonists are nearly their ages as well. All the tension does not stem from an environmental experiment gone wrong, where grasshoppers are the size of camels and praying mantises are as big as giraffes.
The children do not get along that well either. Add to that predators that just want to eat them, and the inside of Jupiter seems far from a happy wonderland.