Family Aleyrodidae 
Whiteflies 
Members of this family are very small mothlike insects, usually less than 2 or 3 
mm in length. The adults all have four wings each. The wings, covered with a 
powdery wax, are whitish in appearance. The larvae are very small and scalelike; 
they are usually found surrounded or covered with a waxy secretion on the 
undersides of the leaves of the host plant. Whiteflies are most abundant in tropical 
and subtropical regions, but a few species have been recorded as far north as New 
England. 
The mulberry whitefly, 7etraieurodes mori (Quaintancé), feeds on mulberry, 
dogwood, azalea, hackberry, hoily, mountain-laurel, basswood, maple, and syca- 
more. The larvae are less than | mm long, jet black, and ringed around with a white 
fringe. Adults are active from June to September. The rhododendron whitefly, 
Dialeurodes chittendeni Laing, an introduced species, feeds on rhododendron. The 
adult is pale yellow; the larvae and pupae are greenish yellow. Infested leaves have a 
yellow, mottled appearance, and their margins curl. The citrus whitefly, D. citri 
(Ashmead), feeds on chinaberry and on crapemyrtle in Florida. The azalea white- 
fly, Pealius azaleae (Baker & Moles), feeds on azalea as far north as Rhode Island 
and Ohio, and sometimes causes severe defoliation. Aleurochiton forbesii (Ash- 
mead) feeds on maple. 
Superfamily Coccodidea 
Scale Insects 
Scale insects are among the most destructive pests of shade trees, ornamentals, 
and greenhouse vegetation, and may cause serious damage to forest growth. Injury 
apparently results from the ingestion of large amounts of plant sap and from the 
production of honeydew, which serves as a substrate for the growth of sooty mold. 
As with aphid honeydew, many beneficial species feed on this material. Plant 
deformation and toxin injury are produced by a few scale insects. 
Adult female scales lack wings, may have legs, and are saclike with no definite 
head, thorax, or abdomen. Adult males are more insectlike in appearance, usually 
with one pair of wings, one pair of “halteres,”’ long legs, and a definite head, 
thorax, and abdomen. Adult males are rarely collected because they are small and 
normally live only a day or two. Most scale insects produce a waxy secretion that 
covers the body either as a shieldlike structure separate from the body or as a 
coating on the body surface. The wax varies from a thin, translucent sheet to a 
thick, wet mass or to a powdery bloomlike secretion. 
Some scale insects are host-specific, but others feed on a wide variety of plants. 
Because of the small size and cryptic appearance of most of these insects, many 
pest species have been distributed inadvertently by commerce as plant contami- 
nants. 
Natural dispersal is primarily by highly mobile windblown crawlers or first 
instars, but dispersal by birds and mammals has also been suggested. In most 
instances, instars other than the crawler are relatively sessile and are unimportant in 
natural dispersal. 
The life stage most susceptible to chemical control is the first instar, apparently 
because during part of this stage there is little or no protective wax covering on the 
insects. Attempts to control other life stages are frequently unsuccessful. There- 
fore, for effective chemical control, it is important that information on the life cycle 
be available so that insecticidal spray applications coincide with crawler 
emergence. 
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