Eriophyid mite infests the upper portion of the developing nut under the perianth and suck the sap. Appearance of elongated white lines below the perianth which later develop into triangular yellow patches. As the nuts mature, the patches turn brown and form longitudinal fissures finally appear as warts on nut warts on nut surface.

Life cycle of mite is completed in 7-10days. Under favorable conditions these mites multiply enormously. The mite is microscopic creamy white slender organism, long elongated and cylindrical. Adult female mite is 200-250 m, long and 36-52 m,  wide.  It has an anterior cephalothorax and an annulated tapering abdomen with two pairs of legs and needle like  mouthparts, which are anteriorly placed. Finely ringed body is beset with bristles arranged in rows. Dispersal is mainly through wind. Hence they can spread very fast.  Incidence is occurred through out the year with a peak during April-May.