Two spotted spider mite. Coloured scanning electron micrograph (SEM). Two-spotted spider mite (Tetranychus urticae) is a pest of many crops throughout the world. Despite their small size, they are capable of very rapidly doing severe damage, due to their great reproductive capacity. There are more than 1200 species worldwide and many of them are major crop pests. The two-spotted spider mite (Tetranychus urticae) is by far the most important species in greenhouses and many outdoor crops. Magnification: x 75 when printed at 10 centimetres wide.