(Diptera) This order includes about 240,000 species spread all over the world. The insects of this order are usually small, with a soft body and metallic luster, covered with hair and sometimes with some scales. Their head is supported by a delicate neck. They have big compound eyes with three simple eyes that can be missing. Their mouth parts are mutated to form proboscis in order to absorb or puncture and absorb. While their forewings are triangle-shaped, membranous and elongated, the rear wings are reduced and replaced by two small chitinous pin-shaped parts called “balance pins”. The function of the balance pins is to adjust the balance of the insect while flying. The insect metamorphosis type is complete (egg - larva - cocoon – complete insect). Larvae usually look like worms without legs. A large number those species are of agricultural, health and veterinary importance. While most species of flies feed on organic materials or flower nectar; others live as parasites on blood of vertebrate. Some species are predators that are very important for biological control. However, larvae feed on different food. Some larvae live in water like mosquitoes; others live in the soil, and some in decomposing materials. Some also live in dung and stool like larvae of domestic flies, whereas others live on plant materials or as parasites on insects and vertebrate animals.
