Shrubs and bushes are a staple in landscapes where the 2- to 20-feet-tall, multi-branched, woody plants help to bridge the gap between the low-growing perennials and annuals and the taller trees. Bushes and shrubs are just as susceptible to diseases and pest infestations as other plants. Common pests include some types of tiny white insects. Proper identification of pests is the first step toward effective management.
Shrubs and bushes are susceptible to infestation from tiny white pests such as aphids, mealybugs and whiteflies. Of the three, aphids are the most common insect of plants including ornamental plants, shrubs and trees, according to the Colorado State University Extension.
Aphids are soft-bodied, oval-shaped and rarely exceed 1/8 inches in length. The winged or wingless insects range in color from a waxy, woolly white to light yellow, red, orange, green or black. Mealybugs have long, segmented, soft bodies and range anywhere between 0.05 to 0.2 inch long. The males are a dirty white to gray color and the females are covered with white, cotton-like wax. Whiteflies have yellow bodies and white wings. The pests are very small in size and the nymphs are wingless.
Aphids, whiteflies and mealybugs are sap-feeding pets that suck plant juices from tender areas like succulent stems, foliage and buds. Greater presence of pests leads to curled, distorted and yellowed foliage with stunted shoot growth. Certain aphids cause galls to appear on damaged areas. As they feed, all three pests secrete a sticky honeydew that leads to the growth of black, sooty mold fungus on infested areas.
Introducing natural aphid predators like the parasitic wasp, syrphid fly and lacewing to infested bushes is among the biological control options for aphids. Chemical control options include the use of pesticides containing acephate, malathion or permethrin. Parasitic wasps, insecticidal soap and narrow range oil are helpful in controlling mealybugs. Forceful jets of water also help to remove mealybugs from plants. Use minute pirate bugs and big-eyed bugs to control whiteflies. Whiteflies are very hard to control with insecticides. Recommended products include neem oil and narrow range oil.
- Colorado State University Extension; Deciduous Shrubs; R.A. Cox and J.E. Klett; April 2007
- Colorado State University Extension; Aphids on Shade Trees and Ornamentals; W.S. Cranshaw; February 2009
- University of California Extension; Aphids; M.L. Flint
- University of California Extension: Mealybugs
- University of California Extension: Whiteflies
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