PREFACE Vll 



W. B, Herms of the University of California; and the MacMillan Co., 

 the Comstock PubHshing Co., Henry Holt and Co., and P. Blakiston's 

 Son and Co., for permission to use certain illustrations from their 

 entomological publications. 



To Mr. E. M. DuPorte, M. Sc, of Macdonald College, the author is 

 specially indebted for the drawings illustrative of the structure of 

 insects in Part I, for valuable criticisms, and for substantial help in 

 proof-reading. 



W. LOCHHEAD. 

 Macdonald College. 



