Abstract: An emitter is provided with a flexible diaphragm of elastomeric material containing at least two slits which radiate outwardly from a point near the center of the diaphragm, the diaphragm being assembled in the emitter body in the manner of a gasket, and the diaphragm having characteristics of durometer hardness and flexibility such than when in use the diaphragm is distended and the slits open to establish an orifice which allows an outflow of irrigating water at a low discharge rate, but when the pressure is removed the resilience of the diaphragm closes, the faces become contiguous and close the orifice, thereby preventing ingress of insects and egress of moisture.