THYSANOPTERA AND ORTHOPTERA. 187 



Habitat determined chiefly by food. 

 Anaphothrips striatus 

 Anthothrips verbasci 



Aptinothrips rufus (with its var. connaticornis) 

 Baliothrips hasilis 

 Ctenothrips hridwelli 

 Heterothrips salicis 

 Phyllothrips aspersus 

 Phyllothrips citricornis 



Habitat determined chiefly by protection. 



Aeolothrips fasciatus 

 Anthothrips niger 

 Chirothrips manicatus 

 Eiithrips tritici 

 Eiithrips fuscus 

 Scirtothrips ruthveni 

 Thrips physopus 

 Thrips tabaci 



Factor determining habitat doubtful. 



Allothrips megacephalus 

 Neothrips corticis 

 Trichothrips beochi 

 Trichothrips tridentatus 

 Trichothrips brevicritralis 



The last group, comprising the doubtful species, is made necessary 

 because specimens have been taken in too small numbers to justify a 

 classification. It seems probable that the phloeophilous species (Allo- 

 thrips megacephalus, Neothrips corticis, and Trichothrips tridentatus) 

 will be found only on bark, and the few collections made suggest that 

 some may be so highly specialized as to inhabit almost exclusively the 

 bark of one species of tree. 



Whether this is to be taken as indicating that the insects are influ- 

 enced by food, or by protection, to choose the bark habitat can only be 

 decided when the food of phloeophilous species is known. It is con- 

 ceivable that they may feed upon the bark itself, or upon mucor or 

 lichens growing on the bark. Several guesses have been made on this 

 point, without, however, any evidence in support of them. I am un- 

 willing, until more data are at hand, to hazard a conjecture as to the 

 factor determining their habitat. 



