INSECUTOR INSCITI^ MENSTRUUS 55 



get 973 species of thrips for North America. Assuming again 

 that the same proportion exists throughout the world, and that 

 there are 150,000 described Coleoptera, we get 6,637 as the 

 total number of Thysanoptera which will have been described 

 from the world when that order is as well worked as the 

 Coleoptera are at present. Certainly not more than four-fifths 

 of the North American nor half of the world's Coleoptera are 

 known. At this proportion the North American Thysanoptera 

 will, when described, total nearly 1,200, while the number of 

 species in the world will fall only slightly short of 13,000. 



If, instead of the beetles, the birds be taken as the basis for 

 calculations, and the assumed number of North American Thy- 

 sanoptera (1,200) multiplied by 25 (the proportion existing 

 between the avifauna of the world and that of North America), 

 the result is 30,000 species of Thysanoptera. 



After taking the mean of several such estimates, the author, 

 in 1915, in a paper read before the Biological Society of Wash- 

 ington, placed the number of existing forms of thrips at 

 25,000.1 ^hjs is considerably less than Mr. C. B. Williams' 

 estimate made to the author in 1914. He is of the opinion 

 that nearly 50,000 species will ultimately be described. 



Suborder TEREBRANTIA Haliday 



Superfamily ^OLOTHRIPOIDEA Hood 



Family .^JOLOTHRIPID^ Uzel 



1. JBolothrips bicolor Hinds. — July 13 ; one female, taken 

 by sweeping. Known previously from Massachusetts, Florida, 

 Tennessee, and Indiana, but occurs also in New York, Vir- 

 ginia, Maryland, Minnesota, Illinois, Kansas, and Texas (coll. 

 Hood). 



2. Molothrips annectans Hood. — April 18 and May 14 ; two 

 females, taken by sweeping (P. R. Myers and L. O. Jack- 

 son). Described from Maryland, Virginia and New York. 



3. Molothrips crassus Hood. — May 19 and 23 ; several fe- 

 males in flowers of water-leaf ( Hydro phylliim virginicum L.) 



»See Science, N. S., Vol. XLI, 1915, p. 877. 



