This monograph is an English translation of one of a series on aphids and whiteflies written by Dr. Hermann Weber. This particular work, originally published in 1935 as volume 89 of the serial Zoologica, contains a series of exquisite plates detailing the anatomy of adult whiteflies. To our knowledge, the work remains unequaled in its attention to anatomical detail of these tiny insects. It seems to us that there is little chance that such an endeavor could be completed today. This translation was carried out at a time when populations of a species of whitefly, Bemisia tabaci, strain B. (also known as B. argentifolii) have erupted in many subtropical countries, causing extensive damage to agriculture around the world. This pest, which is anatomically very similar to the species detailed by Weber, is difficult to control with standard practices; new methods of control are needed. A thorough knowledge of the anatomy of these insects is valuable in understanding how these insects function and, therefore, how they might be brought under control. It is hoped that the translation will make this valuable work by Dr. Weber available to a wider audience.