Provided herein are modified insects having decreased expression of a testis specific coding region compared to a control insect. In one embodiment the modified insect includes the characteristic of reduced fertility reduced fecundity or a combination thereof when compared to the control insect. Optionally and preferably the competiveness of the modified insect is not significantly reduced compared to the control insect. Also included herein are methods for making a modified insect and methods for using the modified insects including making populations of modified insects and use of the modified insects in sterile insect technique for biological control.
