THYSANOPTERA AND ORTHOPTERA. 217 



ORTHOPTERA. 



INTRODUCTION. 



The collection of Orthoptera obtained on the Biological Surve\' dur- 

 ing the summer of 1908 was of all the groups of insects, except the 

 Thysanoptera, the most representative. While the collection is not 

 supposed to be complete, the number obtained in the various families 

 and the data secured both for individual specimens and for certain 

 groups as a whole, seem to call for a separate report. The group is so 

 much better known than the Thysanoptera that little was attempted 

 in a biological way except the ecology. This little included some ob- 

 servations of economic interest. The almost uniform nature of the 

 small region studied prevented the finding of a great variety of Ortho- 

 ptera and made it impracticable to work out any consistent scheme of 

 ecology for the whole order. The results are therefore given largely 

 in detail without any attempt at present to relate the facts to each other. 



For the identification of the collection, I am indebted to Prof. A. P. 

 Morse. 



ECONOMIC CONSIDERATIONS. 



The agriculturist is accustomed to look upon grasshoppers, crickets, 

 etc.. as a .sort of harmless annoyance. Except in certain regions they 

 have never appeared in such numbers as to carry devastation vrith. 

 them. Few people, therefore, realize the economical importance of 

 these insects, or have a knowledge of the amount of damage they may 

 do under ordinary circumstances. 



An opportunity to test their damage, in what seems to me to be a 

 fairly accurate way, was presented in the latter part of the period spent 

 in the field. In general, the method consisted in determining the num- 

 ])er of Acridiidae present on a given area, and the amount of vegetable 

 matter eaten in a given time by a single individual. The former de- 

 termination was made in a field of blue grass and timothy where Ac- 

 ridiidae of various species were c^uite abundant, but not more abundant, 

 I believe, than they often are. The conclusions I reach, therefore, 

 will apply, not to an average season, but to what would be called in the 

 northern or eastern states "a grasshopper year''. 



The details of counting the grasshoppers were as follows: I would 

 move cautiously into the grass so as not to flush the insects until I had 

 approached within several feet of them. Then fixing my eyes on some 



