BIOLOGY OF THE THYSANOPTERA 1 



DR. A. FRANKLIN SHULL 

 University op Michigan 

 I. FACTORS GOVERNING LOCAL DISTRIBUTION 

 Introduction 



The Thysanoptera, commonly called thrips, are only 

 beginning to be known, in this country, by systematic 

 entomologists. The systematic knowledge is mostly con- 

 tained in the monograph of Hinds (1902), a more recent 

 synopsis by Moulton (1911), and a few other papers deal- 

 ing with new species and with relationships, prominent 

 among which is the work of Jones (1912). Biologically 

 the group is still less known. A considerable number of 

 papers have been issued from experiment stations, de- 

 scribing the life history (egg, larval, pupal and adult 

 stages) and habits of thrips of economic importance. Be- 

 sides these the principal recent work of a biological 

 nature is a paper of my own (Shull, 1911), on the ecology, 

 method of locomotion, mode of reproduction, and dissemi- 

 nation. The life cycle of most species is still largely un- 

 known. 



The first section of this paper is an attempt to carry 

 into further detail the study of the ecology of the Thy- 

 sanoptera. The first ecological scheme, so far as I am 

 aware, worked out for the Thysanoptera was that of Jor- 

 dan (1888), who divided thrips into three classes: first, 

 the flower-dwellers ; second, the leaf -dwellers ; and third, 

 all other thrips (for example, those living on fungi, under 

 wet leaves, under bark of trees, on roots, on lichens, etc.). 

 The inadequacy of this classification, and the difficulty of 

 applying schemes of ecology adapted to other groups of 

 insects, was pointed out in my earlier paper, where I pro- 



1 Contributions from the Zoological Laboratory of the University of 

 Michigan, No. 142 (Biological Station Series, Zoological Publication, 

 No. 10). 



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