INTRODUCTION. 9 



Twenty thousand eggs have been estimated on a large orange leaf. From observa- 

 tions made in the laboratory, egg-laying begins when the female is from eighteen to 

 thirty hours old ; and from seventeen to twenty-five eggs are deposited. These eggs 

 are generally all laid within twenty-four hours after the first egg has__hen laid. Her 

 length of life has been estimated at from three days in warm weather to three weeks 

 in cool weather, and the complete length of life cycle from egg to adult is from forty 

 or fifty days in summer to six months in winter. 



The origin of the whitefly pest in Florida is only a matter of con- 

 jecture. It is not definitely known whether it is a native species or was 

 introduced from the East. A recent report that Aleyrodes citri has been 

 discovered in Asia gives some weight to the latter view. H. A. Gossard, 

 in Bulletin (>T of the Florida Experiment Station, "The Whitefly", 1903, said 

 with regard to its advent in Florida : 



The fly seems to have been first known in Florida throughout the region comprised 

 in Volusia, Marion, Lake, Alachua, and Orange counties ; from which, I have little 

 doubt, it was transferred to Manatee county and to local centers along the northern 

 borders of the State. 



It had therefore become widely distributed before it attracted any consid- 

 erable attention. At the present time it is widely distributed in many parts 

 of Florida, and is spreading slowly to parts not before infested, in spite of 

 the work that is done by the growers to keep it out of the groves. 



Several investigations are being carried on at the present time by the 

 Florida Experiment Station, and by the United States Department of Agri- 

 culture in order to work out practical methods of controlling the pest. 

 Spraying with insecticides, fumigation with hydrocyanic acid gas under 

 tents, and infection with fungus parasites have all been used. Fumigation 

 and fungus infection are the most promising remedies known at the present 

 time. The use of the fungus parasites in destroying this insect will be 

 briefly discussed later, when the various fungi are described. 



The most serious injury caused by the whitefly is the sooty mold that 

 always follows the insect. This is a species of Meliola, a soot-colored 

 fungus that lives in the honeydew secreted by the whitefly larvae. Since 

 the larvae are found upon the under surfaces of the leaves, the honeydew 

 collects upon the upper surfaces of the leaves below and furnishes a suita- 

 ble medium for the growth of Meliola. The sooty mold spreads in a black 

 layer over the surface. The fruit is also blackened, so that it must frequently 

 be washed before it is shipped. The vitality of the tree is lowered, not 

 only by the loss of the nourishment sucked out by the insects, but also by 

 the shutting off of the sunlight from the surfaces of the leaves. An account 

 of this fungus is given by Webber in Bulletin 13 of the Division of Vegetable 

 Physiology and Pathology, Washington, D. C. 



