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.

Insects - External morphology

Basic external features of an insect

The body of an insect is mainly divided into three parts

• Head
• Thorax
• Abdomen

Head contains Antennae, Compound eyes and the mouth parts. Thorax comprises three segments. Usually the thorax bears the legs and the wings.  

Abdomen is consist of 7-11 segments with appendages.

Parts of a leg

Mouthparts

Mouthparts are adapted for feeding. Mainly there are two types.

• Chewing and biting mouthparts
• Sucking mouthparts

Chewing and biting mouthparts of cockroach

Siphoning mouthparts of butterfly

piercing and sucking mouthparts of mosquito

Sponging mouthparts of Housefly

Lapping mouthparts of honeybee

                   

Antennae

Different kind of insects

Silverfish

Head louse

Thrips

Flea

Damselfly

Dragonfly

To know about how to make a bug collection visit http://www.cnr.berkeley.edu/citybugs/studentcorner/MakeABugCollection/MakeABugCollection.htm