Aphids

• Aphids are common garden pests that live on a variety of plants in the garden and landscape, as well as indoor houseplants. They typically cluster around the young leaves and shoots on tomato plants. While many aphids are green, these little bugs may also be yellow, black, gray or red. Aphids have tiny, soft bodies that measure about 1/8 inch long. Aphids only live between one and two weeks, quickly laying eggs that hatch into new offspring. Only intermittent generations of aphids have wings that allow them to fly from plant to plant.
  
  

Damage

• Aphids seldom kill entire tomato plants, however, abundant feeding may remove large quantities of sap, resulting in stunted growth and poor fruit formation. While they prefer feeding on the leaves, they may also eat away at the blossoms, minimizing the amount of available fruit at harvesting time. Signs of damage include curling leaves, leaf scald and stem wilt.
  
  

Prevention

• A healthy tomato plant is the best line of defense in preventing damage from aphids. Tomato plants prefer well-drained, rich soils with adequate water. Abundant sunlight will strengthen the plants and help them withstand pest infestations. Biological controls are beneficial in managing aphids and preventing large infestations. Insects that limit the aphid population include damsel bugs, tiny wasps, lady beetles and syrphid fly larvae.
  
  

Treatment

• Large infestations may require pesticide treatments to save the life and health of the infested tomato plants. The rule of thumb in using pesticides to kill green aphids on tomato plants is to begin treatment when aphids appear on 50 percent of the leaves. Pesticide sprays that include insecticidal soaps or oils work by smothering the aphids. Some products require a second application several days later to both the adults and the eggs.