CLASSIFICATION OF THE ALEYRODIM-PART I. 
INTRODUCTION. $ 
Few groups of insects have been more neglected by entomologists 
and collectors than the Aleyrodida?. It is believed that compara- 
tively few of all the species which undoubtedly exist have as yet 
found their way into collections. The family is widely distributed 
in the temperate and tropical regions of the world, and it will per- 
haps, when thoroughly worked, prove to be about as rich in species 
as the Coccidae or Aphididse. 
Beginning with Maskell's paper, which appeared in 1895, there have 
followed a number of publications dealing with the Aleyrodidge, 
most of them systematic in character, but some dealing with the 
biology and habits of certain species of considerable economic im- 
portance. These papers have come from widely separated parts of 
the world, as New Zealand, the United States, India, Europe, Japan, 
etc., and indicate an increasing and widespread interest in these 
insects. 
Until 1907 only two genera for the family were recognized, Aley- 
rodes and Aleurodicus. Since this date, however, three additional 
genera have been established, namely, Aleurochiton, Paraleyrodes, and 
Udamoselis, the discovery of which has thrown much light on the 
probable position of the Aleyrodidse in relation to other families 
of insects, and on the lines of descent of the several subgroups within 
the family itself. 
The insect collections of the United States National Museum and 
of the Bureau of Entomology contain a large amount of material of 
this family received from correspondents from many parts of the 
country, and have been recently considerably augmented by the 
large series of specimens attained by Mr. E. S. Woglum, of the 
Bureau of Entomology, in connection with his search for natural 
enemies of the citrus white fly {Aleyrodes citri R. & H.) in the 
Orient. The bureau also has, as stated in an earlier publication, 
through the kindness of the New Zealand Institute, the temporary 
custody of the Maskell collection of Aleyrodidse, including nearly 
all of his types. It has therefore seemed appropriate to undertake, 
at this time, a revision of the group as a whole, and to determine as 
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