Baker & Holes. — the aleyrodid.ií of south america 611 



the liost plaut. Etirely, however, are the early stages in 

 the latter places. The eggs are elongate-oval, brown, yel- 

 loAV, or light green iu color añd are placed on the leaf by 

 means of a stalk of varying length. They are usually laid 

 iu a more or less spiral or circular arrangement but raauy 

 species place them irregularly. The body of the adult is 

 sinall and delicate iu color, with white rouudel wiugs, 

 either uuraarked or with small dusky áreas. It is with the 

 pupal stage that we are raostly concerned, as the charac- 

 ters in this stage are the ones used mostly iu thedeterrai- 

 nation of the genera and species, and the destructiveness 

 of the insect is produced in this stage. The pupae and lar- 

 vae are oval in shape, ñattened, quiesceut on the leaf 

 during the three last stages. There are fourraoulting per- 

 iods frora the hatched egg to the adult stage, and during 

 these stages mauy characters are added and many lost. 

 The pupae are generally supplied with wax glands and 

 produce wax in varying amounts which, spread out on the 

 leaf away from the dorsum of the pupae in many beauti- 

 ful patterns. In some species the wax secretion seems to 

 be lackiug or very slight, while in others it is so copious 

 as to cover the whole leaf and body of the insect. 



The white flies seem to attack nearly every type of 

 plant, settling mostly on the under side of the leaves, and 

 while not always seriously damaging the host, they cause 

 many unsightly blemishes where the pupal stage of the 

 insect has rested. When the infestation is serious the lea- 

 ves may curland drop off, and even though the leaves do 

 not drop the resistance of the plant is so lowered that it 

 becomes a prey to other insect pests and fimgi. The larval 

 forms are attacked by fungous and insect parasites, and 

 both may act as means of control. 



The greater part of the systematic work on this 

 group has been done since 1895, after the publication of 

 Maskell's paper. From that time until 1907 only two gen- 

 era of the family were recognized, Aleyrodes and Aleu- 

 rodicus. With the publication of the Avorks of Quaintance 

 and Baker a system of classification was Avorked out bas- 

 ed upon the natural relatiouships of the various forras, 

 the family as a whole revised, keys made, and many new 

 genera and species described. Many smaller papers have 



