250 



ARTHROPODA 



[CH. 



Hemiptera there is no quiescent pupa stage and the chief difference 

 between the larva and adult is the absence of wings in the former. 

 Here the metamorphosis is said to be incom- 

 plete. The same is true of Ephemeroptera, 

 Isoptera and Paraneuroptera. Amongst the Le- 

 pidoptera, Coleoptera, Hymenoptera and Diptera 

 there is a well-marked pupal stage, and these 

 orders are said to have complete metamorphosis. 

 Various names have been given to the larvae of 

 Insects without very precise definitions. Those of 

 the Lepidoptera are usually called Caterpillars. 

 They are often gaudily coloured and bear tufts 

 and bunches of hair. Besides the three pairs 

 of legs which are found on the three segments 

 following the head and which correspond with 

 the legs of the imago, certain of the abdominal 

 segments bear fleshy stumps called abdominal 

 The larvae of some of the Saw-flies (Hymenoptera) have 

 a similar bright colouring and resemble Caterpillars, and like 

 them feed exposed on leaves, etc. The larvae of Beetles and most 

 Hymenoptera are as a rule hidden underground or in galls or wax- 

 comb. They are whitish in colour and unattractive, and are often 



Fm. 103. Cocoon of 

 Bombyx won, from 

 which silk is spun. 

 About life size. 



B 



FIG. 104. Silk-worm moth, Bomlyx mori, 

 A. Female. B. Male. 



termed grubs, whilst tlje footless white larvae of the Diptera, 

 which are for the most part deposited in some organic substance 

 whether alive or not are usually called maggots. The wingless 

 young of Orthoptera and of the other orders in which incomplete 

 metamorphosis occurs are termed nymphs. 



In the following account of Insect Classification we can only 

 indicate the chief characters of each order and mention the names 

 of one or two common members of each. 



