This paper describe about how a mobile phone can be a piece of equipment or tools used by student to identify various kinds of insect. This mobile application can help their observations and instantly analyzed with quite a lot of data but with fairly simple method that is a key determinant of conventional print media, whether books or sheet form that is practical to be taken by students. To address these difficulties, the key determination method is developed which is based J2ME mobile that can be installed on mobile phones. The key determination was developed specifically to identify these insects can help students to identify different kinds of insect found in students and group them with more practical and more attractive than the conventional determination key. With this application, students can immediately identify the insect on the spot. The key determinant of this mobile includes a description of the characteristics of an organism is presented with the opposite character. These characters are presented ranging from the general character of the increasingly more and more specific until eventually leading to the key characters whose show a particullar species. Keywords: key determinant, mobile, species, taxonomic