SUBFAMILY MONOPHLEBINAE 63 



always present in all nymphal stages and are similar in form. The 

 profemora are never greatly enlarged and the prothoracic legs are never 

 fitted for digging. The body is never provided with an anal cleft and 

 opercula, an anal ring and anal ring setae, anal lobes and anal setae, 

 octacerores, pilacerores, or ceratubae. The caudal end of the rectum 

 is sometimes modified into a strongly chitinized rectal tube provided with 

 one or more rings of anacerores, but not excreting a long glassy tube of 

 wax. The caudal abdominal segment is not short, narrow and projecting. 

 The male has compound eyes and may have an ocellus along the 

 caudal margin of each compound eye. The abdomen is either provided 

 with long lateral filaments or is without such structures, never provided 

 with tufts of long filaments of wax. The stylus is small or wanting. 



The subfamily Monophlebinae contains about fifteen genera 

 and about ninety species. While certain of these genera are 

 limited to species from the old world and others to species from the 

 new world, the larger more important genera contain species from 

 all parts of the world so that they can be said to be universal in 

 their distribution. The species are found mainly in tropical 

 regions but a few extend into or have been introduced by commerce 

 into subtropical and the warmer temperate regions. A few species 

 sometimes become established under glass in north temperate 

 regions. 



Coccids are generally considered as being of small or minute 

 size. This is true of the great majority of 'the species. The sub- 

 family Monophlebinae nevertheless contains some species of 

 considerable size. Species that are twelve millimeters or one-half 

 inch in length are of common occurence, while some of the species 

 of certain genera as Llaveia, attain a length of twenty-five 

 millimeters or one inch. It is not strange, since this subfamily 

 contains the most generalized coccids, that it should include species 

 of considerable size, but species that are of considerable size, not 

 only for coccids, but for insects in general. 



The best known species of this group in America is the citrus 

 pest, the Cottony Cushion Scale or Fluted Scale, Icerya purchasi. 

 The life history of this species, because of its economic importance, 

 has been studied more intensely than that of any other. The 

 following account, based in great part upon the descriptions of this 

 species, is offered in place of a detailed statement of the serial 

 development of the group as a whole, since our knowledge is too 

 limited at this time to prepare such a statement. 



The recently hatched nymphs are reddish yellow in color. 

 The body is ovate in outline with the dorsal surface convex and 

 the ventral aspect more or less flattened. The antennae are long 



