174 



Bulletin 190. 



The depredators proved to be members of a peculiar family of 

 insects known as the Aleyrodes, or popularly as " white-flies " or 

 *' mealj-w^ings ; " ■^' these apt names were suggested by the fact that 

 the adult insects have their four wings covered or dusted with a 

 white, meal -like secretion of wax. Some of these minute " white- 

 flies " are shown about twice natural siz(? at E in flgure 45, and one 

 is shown much enlarged with wings spread at e in flgure 46. At A, 

 flgure 45, and Z», c, flejure 46, are shown some of the peculiar stalked 

 eggs which are attached to the under sides of the leaves, from which 

 hatch in about ten days the active louse-like nymphs shown at B, 

 flgure 45, and d, flgure 46. These nymplis soon settle down and 



ym^"^: 



45. — A common greenhouse Aleyrodes. A, eggs ; B, young nymph 

 or ''larva;'' G, D, dorsal and side vieics of fuU-groion 

 nymph or ''pupa'' {A, B, C, JD, much enlarged). E, adult 

 Aleyrodes or "white-flies" and their eggs on orange leaves, 

 about twice natural siz".. {Be laced from D.ivis.) 



begin to suck out the sap of the plant, gradually increasing in size 

 and flnally in two or three weeks attaining the advanced nymph or 



* We sent some of the infested leaves to Professor Quaintance and he reported 

 that the species was much like Aleyrodes vaporariorum, livX he could not be sure 

 as to the species owing to the rather broken up condition of the specimens and 

 the absence of adults. The above species is the one commonly found in green- 

 houses on various plants. It was described in 1856 by West wood (Gard. Chron., 

 p. 852), and it is interesting to note that he says it is " supposed to have been 

 imported into England with living plants or in the packings of Orchidacece from 

 Mexico." Our American Aleyrodids have been recently monographed by Pro- 

 fessor Quaintance (Bull. 8, Tech. Ser., U. S. Div. Entomology;. Some modern 

 writers use the form Aleurodes, but we have followed the origiual spelling of the 

 word, Aleyrodes, as given by Latreille. 



