(Orthoptera) This order consists of about 20,000 species distributed into 28 families spread in all regions of the world. This order includes the insects known as locusts, hoppers and field crickets. They have big compound eyes in addition to two or three simple eyes that can be missing altogether. Their antennae are moniliform, filiform or pilose. They have a wide head and two pairs of wings, the front pair of which is usually long, narrow and thick, while the rear pair is transparent, membranous and semi-circular. The coxa of the third pair of legs is swollen and long to be used for jumping. The metamorphosis of this insect is gradual (egg - nymph - complete insect). The complete insect squeaks by rubbing the edges of their leathery wings. Generally, males have a device for producing sounds. Insects of this order are sometimes called hoppers .