Orientation of insect head: Prognathous, Hypognathous and Opisthognathous

·         Three types of orientation.

                                i.            Prognathous: orientated horizontally. Mouth parts are pointed forward.

                              ii.            Hypognathous: orientated vertically. Mouth parts are pointed down.

                            iii.            Opisthognathous: orientated obliquely. Mouthparts are pointed backward.

Prognathous

·         Mouthparts are pointing forward.

·         Mouthparts are anterior in position.

·         Long axis is horizontal.

·         Mostly carnivore insects have this type of orientation.

·         Ex: Stick insect

Hypognathous

·         Mouthparts are pointing downward.

·         Mouthparts are ventral.

·         Long axis is vertical.

·         Mostly herbivore insects contain this type.

·         Ex: Grasshopper.

Opisthognathous

·         Mouthparts are pointing backward.

·         Mouthparts are directed down between coxae of legs.

·         This is known as proboscis.

·         Long axis is horizontal.

·         Ex: Plant sucking bugs.