Tiny Green Bugs Are Killing My Plants

Identification

• There are about 5,000 aphid species in the insect family Aphididae. Aphids are usually under 1/8-inch long, with a pear-shaped body and two projections at the end of their abdomen, called cornicles. All aphids have a small, beak-like mouth, ideally suited for sucking plant fluids. Some generations of aphid species develop wings and disperse to other plants when conditions on the host plant become crowded.

Life Cycle

• Aphid eggs hatch in the spring into wingless females. Without mating, these females give birth to live offspring. Reproduction continues this way, producing multiple generations throughout the season. Near the end of the season, a generation of winged males and females appear. They mate and lay eggs, which overwinter in the protected parts of plants, then hatch the following spring.

Symptoms

• Aphid infestations on plants cause curling and wilting of leaves, deformation of stems and destruction of buds. Dark mold on plants provides further evidence of aphid infestations. Mold readily grows on the sugary excrement, known as honeydew, discharged by the insects. Too much mold hinders the photosynthetic process of the plant, potentially killing it. Since aphids feed by inserting their mouths into a plant, aphids can also transmit fatal diseases to some plants.

Control

• Most plants survive infestations with the help of the aphid’s natural predators -- ladybugs, lacewings, wasps and flies. Where predators are absent, or plants are indoors, other control methods become necessary. A strong spray of water or a wipe with an alcohol-soaked cloth destroys aphids on plants. To prevent diseases spread by aphids, the University of California’s Integrated Pest Management Program recommends repelling the pests with reflective mulches.