Scientists at the University of California (UC) San Diego and UC Berkeley have developed a new approach to controlling disease-carrying or crop-destroying insects that uses CRISPR-Cas9-based genome editing to determine insect sex and fertility. The new technology, developed initially in fruit flies as a test case, represents a new take on sterile insect techniques (SITs) that have been used since the 1930s to mass produce and release sterile males as a strategy for eradicating insect populations.