IV MISCELLANEOUS PAPERS. 



Page. 



An internal parasite of Thysanoptera E. M. Russell. . 25 



Introduction 25 



History of the discovery 26 



Classification and original description 27 



Life-history summary of the original host {Heliothrips fasciatus Pergande). . 28 



Methods of collecting for evidence of parasitism 28 



Methods of rearing parasites for life-history study 29 



Stage of thrips showing parasitism 30 



Appearance of parasitized prepupse 30 



Behavior of parasitized thrips 31 



Time between first indication of parasitism and formation of parasite pupae 



under laboratory conditions 31 



Effect of cold on parasitized prepupae 31 



The pupa of the parasite 31 



Formation 31 



Description 32 



Length of pupal stage 33 



Effect of cold on pupal stage 33 



The adult parasite 33 



Emergence 33 



Description of newly emerged, live adult 34 



Relation and proportion of sexes 35 



Parthenogenesis 35 



Method and period of oviposition 36 



Habits in the open 38 



Effect of oviposition in different stages of host 38 



Number of eggs and length of oviposition period 38 



Double parasitism 39 



Activity 39 



Flight 40 



Sight 40 



Behavior on different kinds of leaf surfaces 40 



Host relations 41 



Heliothrips fasciatus Pergande 41 



Thrips tabaci Lindeman 41 



Euthrips tritici Fitch 42 



Heliothrips hxmorrhoidalis Bouche 42 



Heliothrips femoralis Renter 42 



Miscellaneous observations 43 



Summary of experiments to determine host relations 43 



Length of life in confinement 43 



Causes of mortality in the open 44 



Effect of oviposition in different ages of host larvte 44 



Life history 44 



Length of time from oviposition to first ihdication of parasitism 45 



Length of time from oviposition to pupation of the parasite 45 



Length of life cycle 46 



First appearance in the spring 47 



Last appearance in the fall 47 



Number of generations 47 



Hibernation 47 



Occurrence 48 



Distribution 48 



Percentage of parasitism in different localities 49 



Means of colonizing the parasite 51 



Index 53 



