Predator-prey interactions are fundamental to the understanding of ecological communities. The non-consumptive effects of predators on the food web can be more prominent than direct killing. However, the non-consumptive effects in intraguild interaction have rarely been studied. This study determined the non-consumptive effects of an intraguild predator Blattisocius dentriticus on Neoseiulus cucumeris. The responses of N. cucumeris to the predation risk of B. dentriticus adult females were examined in a laboratory test. The developmental response of N. cucumeris to predation risk was sex-specific: the presence of B. dentriticus cues prolonged the immature development of N. cucumeris males and increased their consumption rates of Tyrophagus putrescentiae eggs, but did not affect the development and prey consumption of female N. cucumeris. The size at maturity of N. cucumeris was not affected by predation risk from B. dentriticus. This study demonstrated that intraguild predators can have substantial non-consumptive influence on intraguild prey.