8 Summary of the Characters of Insects, etc. 



This class is divided into the following smaller groups called 

 orders : — 



a. Ooleopiera (Beetles). Wings four, the upper pair hard and 



horny (elytra). A biting mouth present. 

 h. Lepidoptera (Butterflies and Moths). Four wings, more or 



less covered with scales. Mouth suctorial. 



c. Hymenoptei-a (Ants, Bees, Wasps and Sawflies). Four mem- 



branous wings, few veins. Mouth biting and suctorial. 



d. Diptera (True Flies). Wings two only ; the second pair 



reduced to two club-shaped processes called halteres or 

 poisers. Mouth piercing or suctorial. 



e. Hemiptera (Bugs, Scale Insects, Plant Lice). Wings four. 



Mouth piercing and suctorial. The front wings may be 



leathery at the base (hemi-elytra) in Bugs (Heteroptera), 



or all transparent, as in Plant Lice (Homoptera), or absent 



(Scale Insects). 

 /. Neuroptera (Lace-wing and Dragon Flies). Wings four ; more 



or less uniform, with a network of veins. Mouth biting. 

 g. Orthoptera (Locusts and Grasshoppers). Wings four ; front 



pair more or less leathery, veins more or less straight; 



hind pair fan-shaped, with radiating and concentric veins. 



Mouth biting. 

 h. Thysanoptera (Thrips). Wings four; very narrow, fringed 



all around with hairs. Mouth weak, biting. 

 i. Aptera (Springtails, etc.) No wings. No life changes. 



The iirst four undergo what is called complete mctamorpliosis, 

 that is, there are the following stages during growth : — 



(1) The ovum or egg. 



(2) The larva (caterpillar, maggot or grub). 



(3) The pupa or chrysalis. 



(4) The sexual adult. 



The third stage is the one in which the active, sexless larva is 

 transformed into the sexual adult, the period when the caterpillar 

 is transformed into the moth. It is a period of rest and complete 

 change ; the pupa is unable to crawl or fly or feed, a quiescent period 

 when most of the organisation of the larva is broken down and 

 reformed. 



The groups or orders e to h undergo what is called incomplete 

 metamorphosis. Here we have the same stages, namely, egg, larva, 

 pupa and adult, but the pupa is active and feeding. Growth and 



