This paper deals with insects/mites occurring on mushroom collected from different places of  South 24 Parganas district and reports occurrence of  9 species of insects under 8 families and 12 species of mites under 10 families. Out of the total of  21 species, Megaselia scalaris and Musca domestica among insects and Tyrophagus putrescentiae,  Acarus siro and Histiostoma heinemanni among mites are the most damage causing organisms on Oyster mushroom (for insects) and Milk mushroom (for mites). Likewise, Camponotus vicinus (Fam. Formicidae) from insects and Hypoaspis berlese and Lasioseius quadrisetosus among mites are the two predators of much value. All the insects and mites are listed giving their habitats, date of collection, economic importance, if any.