INSECTS INJURIOUS TO CITRUS FRUITS 611 



important (the Woolly Whitefly *) . The last named species is al- 

 most perfectly controlled by a Hymenopterus parasite, 



The life history of all these is essentially the same, as are their 

 habits, and one discussion will fit all reasonably well. 



The eggs are minute objects laid on the under side of the leaves. 

 The young crawl about and begin to suck sap, staying away from 

 the light as much as possible. They soon become stationary, like 

 scales, and remain so until the growth is completed, when they 

 transform to adults which are minute fly-like insects about one- 

 sixteenth inch long. The wings are white and covered with a fine 

 waxy powder. 



Injury from whiteflies is the result of their feeding habits which 

 drain the tree of its sap and also of the production by them of 

 quantities of honey-dew, the effect of which is exactly the same in 

 this case as in the case of the scale insects having the same habit, 

 that is, the growth of sooty-mold on all parts covered with the 

 honey-dew and the consequent interference with the function of 

 the leaf and the necessity which arises for washing affected fruits 

 with the attendant loss from the process. Blackening of the trees 

 from the sooty-mold is the most prominent sign of the presence of 

 the whiteflies in number. 



Control of Whiteflies f 



Whiteflies maybe controlled by spraying and by fumigation. 

 The practice of these control methods as applied to whiteflies does 

 not differ materially from the same methods as used for scales and 

 mealy-bugs. They are therefore all discussed under the general 

 head dealing with control measures for these insects. Another 

 means of controlling the whitefly, and applicable only to it, is the 

 control by the use of parasites or fungus diseases which attack 

 these insects. 



There are four of these diseases which are most important in the 

 control of whiteflies, with but one exception they infect the 

 young insects only. Of these the most important is the Brown 

 Fungus (jEgerita webberi), which appears as brown spots on the 

 under side of the leaves. A young whitefly attacked by one of 

 these spores produces a growth of the fungus from which minute 



* Aleurothrixus howardii, Quaintance. 



t See P. H. Rolfe and H. S. Fawcett, Bulletin 119, Florida Exp. Sta. 



