CONTHNTS 



Page. 



Introduction 25 



History of the discovery 26 



Classification and original description 27 



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



Methods of coUect lug for evidence of parasitism 28 



Methods of rearing parasites for life-history study 29 



Stage of thrips showing parasitism 30 



Appearance of parasitized prepupa; 30 



Beliavior of parasitized tlxrips 31 



Time between first indication of parasitism and formation of parasite pupae un- 

 der hxboratory conditions 31 



Effect of cold on parasitized prepupsie 31 



The pupa of the parasite 31 



Formation 31 



Descripti)n 32 



Length of pupal stage 33 



Effect of cold on pupal stage 33 



The adult parasite 33 



Emergence 33 



Descrij^tion of newly emerged, live adult 34 



Relation and proportion of sexes 35 



Parthenogenesis 35 



Method and period of oviposition 36 



Ilaljits 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 



l>ehavior on different kinds of leaf surfaces 40 



Host relations 41 



Heliothrips fasciatus Pergande 41 



Thrips tabaci Lindemau 41 



Euthrips tritici Fi tch 42 



Heliothrips hsemorrhoidalis Bouche , .• 42 



Ilelinthrips femoral is 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 larvaj 44 



Life history 44 



I>ength of time fr.)m oviposition to first indication of parasitism 45 



Length of tune from oviposition to pupation of the parasite 45 



Length of life cycle 46 



First apy)earance 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 



III 



