Phylloxera caryaecaulis (Fitch), the hickory gall aphid, is a 
common species that produces almost spherical galls, 16 to 18 mm. 
in diameter, on the twigs and leaf stems of hickory. The galls are 
green when first formed; later, after the aphids vacate them, they 
turn brown or black. The pecan phylloxera, P. devastatrix Per- 
gande, and the pecan leaf phylloxera, P. notabilis Pergande, pro- 
duce galls on pecan. P. rileyi Riley is found on white and post 
oaks, and P. nyssae Pergande infests blackgum. 
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 white powdery wax, are whitish 
in appearance. The larvae are very small and scalelike and 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, Tetraleurodes mori (Quaint.) feeds on 
mulberry, dogwood, azalea, hackberry, holly, mountain-laurel 
basswood, maple, and sycamore. The larvae are less than 1 mm. 
long, jet black, and ringed around with a white fringe. Adults are 
active from June to September. The rhododendron whitefly, Dia- 
leurodes chittendeni Laing, an introduced species, feeds on 
rhododendron. The adult is pale yellow; the larvae and pupae 
greenish-yellow. Infested leaves have a yellow, mottled appear- 
ance, and their margins curl. The azalea whitefly, Pealiws azaleae 
(Baker & Moles), feeds on azalea as far north as Rhode Island 
and Ohio, and sometimes causes severe defoliation. Alewrochiton 
forbesi (Ashm.), feeds on maple, and the citrus whitefly, Dialewr- 
odes citri (Ashm.), feeds on chinaberry and on crapemyrtle in 
Florida. 
SUPERFAMILY COCCOIDEA 
(SCALE INSECTS) 
Seale insects are among the most destructive agents of shade 
trees and ornamentals. At times they may also cause serious dam- 
age to forest growth. Injury results either from the withdrawal 
of sap or the production of galls while feeding. 
Male scale insects are usually winged but the females are en- 
tirely wingless. Adult females also either have no appendages, or 
they are atrophied. As a result, the body is either scalelike or gall- 
like. It is also covered with wax, either in the form of powder, 
tufts, or plates or as a thin layer covering the insect. Females usu- 
ally appear formless because of the difficulty of separating their 
bodies into head, thorax, and abdomen. 
Some scale insects are highly specific in their selection of hosts; 
others feed on a wide variety of hosts. Because of their habit of 
feeding on many different parts of plants, many species have been 
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