They say mosquitos use CO₂ and heat to find hosts more than sound. So repelling via ultrasound might be fighting the wrong clue.
@BuzzBaneBea Did you place the unit near the bed or higher up? I read that height and direction matter a lot for sound waves to reach your sleeping area.
I use ultrasonic + sticky traps + fan. The fan blows away resting mosquitoes, the traps catch active ones, and the repeller maybe helps with stragglers.
If you’re outdoors, wind just scatters the sound waves. I saw much better results with screens and mosquito netting than any electronic gadget.
Some newer models use variable frequency or pulsed signals to break adaptation. Fixed tone ones are too easy for insects to tune out.
I’d trust fans, nets, and regular sprays more than ultrasonic. But I’ll admit, I still keep a small unit near the crib just in case.
I set a UV mosquito trap near my patio plus a repeller. The trap did all the heavy lifting; the ultrasonic may have discouraged some strays.
If you have curly hair, pillows, blankets, etc., they block sound paths. I moved mine to a clear corner with direct line to bed and saw a bit better effect.
Until I see rigorous, peer-reviewed studies showing consistent mosquito knockout, I’ll treat the devices as bonus, not primary defense.