False spider mites
found on the underside of leaves where they cause a brown, scabby discolouration spreading from both sides of the main vein into the leaf blade. The damage [...] are mostly found along the veins on the underside of leaves. The mites are flattened and egg-shaped when seen from above, with their dorsal surface showing [...] of the plant. In some crops, plants can become misshapen, presumably because the mites secrete a substance while feeding, that is poisonous to the plant