37 



Fig. 31.— White fly (Aleyrodes citri) : a, orange leaf, show 

 ing infestation on under surface — natural size; b, egg 

 c, same, with young insect emerging; d, larval insect 

 e, foot of same; /, larval antennse; g, scale-like pupa 

 h , pupa about to disclose adult insect; i, insect escaping 

 from pupal shell; j, leg of newly emerged insect, not 

 yet straightened and hardened — all figures except a 

 greatlyenlarged(reengravedfromRileyandHoward). 



The white fl}" is limited, economicallj^, to the citrus plantings of 

 Florida and the Gulf region. It is widely distributed in greenhouses, 

 as already noted, and has undoubtedly been carried to California on 

 many occasions, but has never gained a foothold out-of-doors. The dry 

 hot season of southern Cali- 

 fornia probablj' accounts for 

 this, and ma}^ prevent its ever 

 becoming troublesome in that 

 region. Its origin is unknown. 

 It first came into prominence 

 about 1885, but probably had 

 been present in greater or less 

 numbers for a much longer 

 period, and perhaps is native 

 to Florida. 



While closely resembling a 

 scale insect in its earl}^ stages, 

 the white fly in the adult stage 

 emerges, in both sexes, as a 

 minute white gnat, having four 

 chalky wings of a line gland- 

 ular texture, from which fact 

 it is frequently called the "mealy wing." This active adult condition 

 gives the white tiy a distinct advantage over scale insects in means of 

 spread. 



The damage occasioned by it is greatly increased by the secretion, in 



the larval and pupal stages, 

 of a honej^dew similar to that 

 secreted b}'^ the true scale in- 

 sects. This is in enormous 

 amount, and the sooty mold 

 which develops in it frequently 

 covers the entire upper sur- 

 face of the leaves and produces 

 very serious effects on the vital- 

 ity of the plant; the fruit does 

 not ripen properly, is deficient 

 in quality and size, and keeps 

 poorly, involving in addition 

 the expense of washing before 

 it can be marketed. 

 The life round of the insect, briefly, is as follows: The winter is 

 passed in the mature larval stage as a thin, elliptical, scale-like object 

 on the under sides of the leaves. Earl}^ in the spring the transforma- 



172 



Fig. 32.— White fly (Akt/rodcscilri): a, winged male 

 insect, with enlarged view of terminal segments 

 at }>; c, dorsal view of winged female, with enlarge- 

 ments of ovipositor, head, antenna, wing margin, 

 and leg at d, e,f, g, h, i (reduced from Riley and 

 Howard). 



