Diptera
(Greek: in means "two", pteraberarti "wing") is a classification order from the class Insecta (insect) based on its wings which has the characteristic of only using a pair of thin wings that are functional to fly, while another pair is only a stabilizer or as an air velocity detector (or known as halterer) Although there are many insects that can fly, but only diptera is considered a true fly because of this character. Diptera has large facet eyes when compared to its body. The antenna can be short (Brachycera) or long (Nematocera).
other picture
Original picture