To kill whiteflies on plants, use sticky traps to capture them, and crush the traps if they are still alive when you find them. Whiteflies are pests that are worst in climates that have mild winters that do not kill them with hard freezes.
- Set out traps in your vegetable garden
Put yellow sticky traps down among your yams, cabbage, peppers or tomatoes, as these tend to attract the most whiteflies. Make your own trap by mixing powder or liquid dishwasher detergent and petroleum jelly in a one to one ratio and spreading it on yellow card stock, or purchase traps at a home improvement or garden store. Wait a few days for the traps to catch the whiteflies, checking once a day.
- Collect the traps
Pick up the traps, and discard. Crush any traps on which the whiteflies still show signs of life, and place in a trash bag.
- Use preventive maintenance to avoid future infestations
Create a diluted mixture of organic insecticidal soap, following the proportions on the packaging. Apply this mixture to the leaves of the plants affected by whiteflies. Avoid using chemical pesticides, as many strains of whiteflies have developed a resistance to them, you end will instead kill the insects that attack whiteflies, creating an imbalance in the local ecosystem.