152 THK CANADIAN ENTOMOLOGIST. 



diverse from those of the group just mentioned. These differences have 

 led some authors to sei)arate the group into a distinct order, the Thysan- 

 optera, while others have considered them an aberrant family of Hemip- 

 tera, others of Orthoptera, and still others of Pscudo-Neuroptera. 



The most obvious characters are the minute size, the species nearly all 

 ranging between one and two millimetres in length, and being very slen- 

 der ; the long narrow wings with broad fringes, folded liat on the back ; 

 the 2-jointed tarsi without ungues and terminating in a vesicle, and the 

 beak-like mouth parts pointing backward, but composed of free mandibles 

 and maxillae, the mandibles being stylifbrm. 



The European species have been carefully worked by Mr. Haliday, to 

 whom we are also indebted for the only systematic arrangement of the 

 genera. His synopsis enumerates over forty species, and doubtless our 

 American species are quite as numerous, for without there having been 

 any apparent effort to collect them, a fair beginning has been made upon 

 this number. 



Dr. Fitch described four species in his reports on N. Y. Insects, and I 

 understand that his notes contain MS. descriptions of two other species. 

 The former are Phhvoihrips iiiali, P. caryce. T/irlps tritici and Colcothrips 

 tri/asciata. Prof Riley mentions a species (6th Rept. Mo. Insects, p. 

 50) as T/irips phylloxera of his MSS. Dr. Packard has described a 

 species infesting onions (New and Inj. Ins. Little Known, 1870), and 

 Prof. Comstock Li/iiot/irips poap/iat^i/s infesting heads of grass. Other 

 descriptions may have been published of whicli I am not at present 

 aware, and I have collected three species in this State which seem to be 

 undescribed, beside two species which are known. 



The Thripiihe frequent tlie blossoms of various i)lants, but their 

 presence has been variously interpreted by different authors. In West- 

 wood's "Classification" they are spoken of as feeding upon the plant 

 tissues, and numerous instances are cited of their injuries to vegetation. 



Dr. Fitch found his P/i/a-f/irips mali gouging into young apples, and 

 his P. caryw in galls on hickory leaves, but doubted theii agency in form- 

 ing the galls. On wheat he states that T. tritici injures both blossoms 

 and the growing kernels of wheat. Mr. Walsh held the opinion that 

 'I'hrips are carnivorous and very beneficial in their attacks upon plant lice 

 and other insects, and argues that they are found in blossoms and on other 

 parts of ])lants simi)ly in search of tlieir prey. Prof Riley describes the 

 habits of his Thrips p/iylloxcne as attacking the Grape Phylloxera. 



