Not all roaches are pests! In fact, out of the nearly 5,000 species known to science, less than 1% (0.1%, actually) are considered pest species. Most of the remainder are inoffensive dwellers of tropical forests, where they are essential to nutrient cycles. Some species are climbers, and care must be taken to prevent escape, while others are unable to climb glass or plastic and can be kept in uncovered containers. That said, covers are still recommended to maintain humidity, as some species benefit from extra moisture.