LICE. 



279 



possess suctorial mouths and are apterous. The Pedioulidae 

 are parasitic on human beings 

 and mammals, upon whom 

 they may breed with great 

 rapidity (partly by partheno- 

 genesis), under favourable cir- 

 cumstances. The young louse 

 is nearly perfect when first 

 born — in fact these insects 

 retain more or less their larval 

 form throughout life. The 

 three well - known species on 

 human beings are the Head 

 Louse {PMldrius capitis), the 

 Clothes Louse (P. vestirnenti), 

 and the Body Louse (P. in- 

 guinalis). The species found 

 on our domestic animals all 

 belong to the genus Hcemato- 



° ° Fig. 160.— Loose of the Ox (Hmmato- 



pinuS. They are never found j'iiiiis enrystemus), female. (Fleuiing.) 



Cireatly enlarged. 



on the sheep or oat. The 



mouth is formed into a kind of sucking proboscis, which is 



plunged into the skin of the host. 



ORDER ORTHOPTERA. 



The Orthoptera are Earwigs, Cockroaches, Grasshoppers, 

 Crickets, Locusts, Praying Mantis Flies, and Walking-stick 

 Insects. They are characterised by having the anterior wings 

 leathery in texture and narrower than the posterior ones, which 

 are fan-shaped and large. The mouth of the Orthoptera is 

 formed for biting. Many are provided with a curious " musical 

 apparatus'' (grasshoppers, &c.) There is usually a pair of long 

 multiartioulate antennae, and two large compound eyes as well 

 as ocelli, on the head. The prothorax is freely movable. The 



