INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 195 



shorl time move uo more until the adull stage is reached. There are 

 several overlapping hi nods each year. 



Nature of Work.— The immature forms alone are destructive and 

 feed almost entirely upon the under sides of the leaves and are often 

 so thick as to completely cover the surface. Besides sucking the sap 

 they secrete quantities of honey-dew upon which the black smut fungus 

 grows, completely covering the tree and fruit. 



Fig. 17l'. --Tin.-' citrus white fly, Dialeurodes citri (R. & n. i. 

 Larvae and nymphs on orange lea irged six times, i Author's 



illustration, Mo. Bui. Cal. Hort. C 



Distribution. — At the present time Ibis pest is known to exist only 

 in the city of Marysville, where it infests yard trees. Continuous 



control measures have reduced it to almost a minimum. The white fly 

 has keen known to exist at Oroville and near Bakersfield, 112 but in both 

 places seems to have been exterminated. It has keen found in a number 

 of localities in the city of Sacramento, kid all infested trees have keen 

 completely destroyed. 



"-The white fly at Bakersfield was another species, Dialeurodes citrifolii (Morgan), 

 previously known as Aleyrodes nubifera Berger. 



