Stick insects can switch between having sex and reproducing without it. Some stick insects can do both, but eventually, they may only reproduce without sex. Researchers found stick insects that can do both in North America. These insects have different ways of reproducing, but all lose genetic diversity quickly when reproducing without sex. Stick insects that always reproduce without sex also have low genetic diversity. This suggests that the switch to always reproducing without sex happened gradually. Stick insects may stop being able to reproduce both ways because one way becomes more efficient. This could explain why few animals can reproduce both ways.