OTHER MEMBERS OF THE CLASS — INSECTA 197 



every year. The Mexican cotton boll weevil destroyed 

 between ten and fifteen millions of dollars' worth of cotton 

 in Texas in 1903. The weevils and the angouniois grain 

 moth that live in stored grains destroy many million bushels 

 of corn, wheat, peas, and beans every year. Professor 

 Sanderson says that three hundred million dollars is a con- 

 servative estimate of the amount of damage done annually 

 by the Colorado potato beetle, tobacco worm, cotton worm, 

 boll worm, plum curculio, San Jose scale, cabbage worms, 

 chinch bugs, grain weevils, and other insects. 



Chief characteristics of the insects. — Insects have six 

 legs; breathe air directly through a system of tracheal 

 tubes ; pass through certain remarkable changes, or meta- 

 morphoses, in their life history ; possess one pair of antennae, 

 two compound eyes and, in many cases, one or more simple 

 eyes, and usually wings in the adult stage. 



CLASSIFICATION OF THE EXAMPLES 



Branch XI — Arthropoda. 

 Class — Crustacea. 



Subclass — Entomostraca. 

 Order — Cirripedia. 

 Types of Order. 



Lepas species — Barnacle. 

 Balanus porcaius — Acorn shell. 

 Order — Ostracoda. 

 Type of Order. 



Cypris species — Water flea. 

 Order — Copepoda. 

 Type of Order. 



Cyclops species — Water flea. 

 Subclass — Malacostraca. 

 Order — Decappda. 



