The dust production rates of all the known periodic comets, calibrated by the measurements from the 1986 apparition of comet Halley, are ušed to compute their dust input into the region inside the earth orbit, and the resulting dust fluxes at R = 1 AU. The spatial distribution of tho fresh ejecta and the teraporal variations of their accumulation are reconstructed. Tho visible release of dust is evidently insufficient to maintain the zodiacal cloud in equilibrium.
It is suggested that the progressive decay of the dark matter, including extinct cometary nuclei, their fragments, and products of asteroidal collisions, represents the dominant source of
replenishmont of the interplanetary dust complex.