June, 12] TOWNSEXD: WHITE SCALE OF COTTON 257 



south and west and used in irrigation, have carried it in general south- 

 ward especially in the Piura valley, this in direct opposition to the 

 prevailing strong winds. Its late invasion of the lower Piura valley 

 is thus explained. 



The species is recorded in the Fernald catalogue from New Zealand, 

 Japan, Ceylon, Brazil, Grenada, Antigua, Jamaica, Panama, Florida, 

 and a variety from West Africa. Mr. W. W. Froggatt writes me 

 that the locality New Zealand is probably in error, and that Maskell's 

 material probably came from some of the Pacific islands. To the 

 above localities can be added Hawaii (Ehrhorn), Barbados (Ballou), 

 Trinidad (Urich), Ecuador and Peru. The insect affects a great 

 variety of plants. To those already recorded I can add probably 

 twenty observed in Peru, but these are immaterial since the species 

 is practically a general feeder as regards host-plants. 



Some authors believe that H. aspidistnc is the same as the present 

 species, but I believe with Mr. E. Ernest Green that the two are 

 distinct and can be easily separated in practically all cases. I have 

 aspidistnc from Cape Colony (Lounsbury), and Ceylon (Green). 

 I also have H. minor from Ceylon (Green) and find the two forms 

 easily separable on external puparial characters which are supported 

 by the pygidial structure. 



Both Japan and Africa have been suggested by authorities as the 

 native home of H. minor. Professor Cockerell states that Hemichi- 

 onaspis is a genus of the Old World tropics, with a lot of closely related 

 species. H. minor is thus most probably not of American origin. 

 As supporting this view I can state that I have uniformly found it 

 absent from the montana region on the east slopes of the Andes, on 

 four trips that I have made in southern, central and northern Peru, 

 and southern Ecuador. 



The species evidently entered the Piura region at the port of 

 Pa\i:a, where I found it abundant on various plants in November, 

 1909, and heavily parasitized. There are frequent steamer connection 

 and exchange of commodities between Guayaquil and Payta, and the 

 small intermediate ports of Tumbes, Zorritos, Talara and Negritos. 

 The scale occurs at practically all of them. The distance from Paji^a 

 to Guaj^aquil is 221 miles. From Pajiia the scale was probably car- 

 ried cHrect, in shipments by rail, to Sullana in the middle Chira valley 

 and Piura in the Piura vallej', at both of which points it entered 

 the small cotton fields and cotton patches near by, thus gaining a 

 foothold. We may therefore consider the pest of Old World origin, 

 long ago spread to America, and recently brought into northern Peru 

 from the humid coast region of Ecuador. 



Like most diaspine coccids this insect, if left to itself, is able to 



