Complex sentence: This grasshopper is usually solitary, but it has been known to swarm as locusts as it did on the Hawaiian island of Nihoa in 2004, wiping out some 90% of the vegetation on the island.
Split into simpler sentences: This grasshopper is usually solitary, but it has been known to swarm as locusts. A particularly destructive swarming event occurred on the Hawaiian island of Nihoa in 2004, wiping out some 90% of the vegetation on the island.