When the mouth parts of a cockroach are observed, it appears that they are placed in a typical downward arrangement with a smaller upper lip (labrum) and a larger lower lip (labium).This sort of arrangement is called______________________ condition.
1. Hypognathous: The long axis of the head is vertical i.e. at right angles to the long axis of the body. The mouthparts point downwards e.g. grasshopper, cockroach etc.
2. Prognathous: The long axis of the head is horizontal and in line with the long axis of the insect's body. The mouthparts are directed forward. e.g., Stick insect, soldier caste of termites etc.
3. Opisthognathous: The head is reflexed ventrally so that the mouthparts are directed backwards between the coxae of the front legs. e.g., Red cotton bug.