Planet Yasai is native planet of Saiyans. It's been destroyed, as believed, by Saiyans themselves.
It's appearance's mostly desert-like, with no life left on it. That's probably one of the possible reasons why they destroyed it.
Before changes in clime, it was full of vegetables (probably there's name puns of vegetables). Saiyans were collecting them as primitive Human did.
Gravity's 5x bigger than Earth's.
There were living Saiyans mostly. There was one race, which is believed that's destroyed with planet Yasai called Furutsus (singular Furutsu). Furutsus had no tail, they had normal musculature and they were higher than Saiyans. Their IQ's a way larger than average Saiyans. They had no known transformations.
There were no that much insects, but larger species similar to insects. They were hunting for fruit and vegetables until it's climatic changes. After that they became carnivores.
There are mammals also. They are much larger than Human in length and height. They are mostly predators.