CHAPTER XXVII. 



INSECTA. 



Systematic (after Brauer, No. 146) : — 



A. Apterygogenea. 



«. Thysanura {Campodea, Japyx, Machilis, Lepisma). 

 b. Colleinbola (Podura, Sminthurus). 



B. Pterygogenea. 



a. Dermaptera (Forficula). 



b. Ephemeridae. 



c. Odonata {Libcllulidae). 



d. Plecoptera (Pcrlidae). 



c. Orthoptera genuina {Blattidae, Phasmidac, Mantidae, 

 Saltatoria). 



f. Corrodentia (Termitidae, Psocidae, Mallophaga), 



g. Thysanoptera (Physapoda, Thrips). 

 h. Rhynchota. 



Neuroptera (Sialidae, Megaloptera). 



Panorpatae. 



Trichoptera (Phryganea). 

 m. Lepidoptera. 

 n. Diptera. 

 o. Siphonaptera. 

 p. Coleoptera. 

 q. Hynienoptera. 



I: 

 I. 



Homomorpha. 



- Heteromoi-pha. 



I. Embryonic Development. 



1. Oviposition and the structure of the ripe egg. 



Most Insects are oviparous, only a few forms bringing forth their 

 young alive, e.g., the parthenogenetic generations of the Aphidae y 

 many Diptera (Sarcophaga, Tachina, Oestridae, Pupipara, Cecidomyia 

 larvae), the Stylopidae, and a few Coleoptera (many Staphylinidae). 

 The eggs when laid are protected from external injuries in many 

 different ways, either by being glued to some surface or by being 

 deposited in water, below ground, or within the tissues of plants. 

 In the last case the laying of the eggs often gives rise to excrescences 

 on the plants (galls). Insects whose larvae live as parasites in the 



