Types of Garden Enemies
Fig.64
Whiteflies secrete a great deal of honeydew in which dark sooty mold grows profusely. They can be controlled with DDT or parathion.

AZALEA WHITEFLY (Aleyrodes azaleae).
Common on azaleas in the South and rather general in the North on white azaleas with tomentose foliage. Underside of leaves is completely covered with flat nymphs and upper surface with sooty mold. DDT controls the whiteflies but increases southern red mites. I have had a good kill with TEPP.

CITRUS WHITEFLY (Dialeurodes citri).
This species has been practically eradicated in California but remains a problem in Florida and the Gulf States. Trees are stunted, fruit undersized and of poor color. Camellias and other ornamentals are often infested, and the whitefly breeds in large numbers in chinaberry trees, which sometimes have to be eliminated. Two oil sprays a year, May and September, have been used in citrus orchards, sometimes with DDT added.

GREENHOUSE WHITEFLY {Trialeurodes vaporariorum).
This is the common species in greenhouses and gardens, appearing on hundreds of plants. It is impossible to grow gardenias or fuchsias without whiteflies. The upper surface of gardenia foliage is almost always covered with a layer of sooty mold (Figure 64). In northern gardens I expect to find these whiteflies in late summer on ageratum, the upper leaf surface stippled white as if leaf hoppers had been working. I find them on heliotrope, eggplant, tomatoes, gourds, and squash. As houseplant enemies they are common on geranium, coleus, and begonia. Infested plants lack vigor, turn yellow, sometimes wilt and die.

Minute yellowish eggs are attached by short stalks to underside of leaves, usually in a circle. Nymphs remain on the leaf near where they hatch, feeding for about a month. They are flat, oval, pale green, with fine white waxy threads radiating from their bodies. The adult is only 1/16 inch long, yellowish body but pure white wings, very active. It feeds for another month or more. In greenhouses there are several overlapping generations.

Control. In greenhouses parathion or TEPP aerosols arc used, and nurserymen in the South spray outdoor gardenias with parathion. Home gardeners will probably find Malathon a less dangerous substitute. DDT has proved quite effective in controlling whiteflies, and lindane has also been recommended. For house plants the aerosol sold as DX Aero-Spray, containing rotenone and pyrethrum, should prove fairly helpful.

MULBERRY WHITEFLY (Tetraleurodes mort).
This rather striking whitefly is sometimes found on underside of mountain-laurel and azalea leaves as well as mulberry. The oval nymph is black surrounded by a pure white fringe. It does not seem to be very injurious, though the sucking may cause some loss of foliage color.




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