In some cases, these parasites can eliminate high densities of aphids over a few weeks. Predators such as lady beetles, syrphid flies and lacewing also attack aphids. Populations of aphid parasites should be preserved by avoiding unnecessary insecticide applications and by providing acceptable habitat for these beneficials. Avoid other aphid-favored crops, such as lettuce, in adjacent, upwind fields. Intensify field monitoring for aphids when adjacent fields with aphid-favored crops are harvested.
Infestations tend to be erratic in the field so sample several locations.
Sample intermediate age petioles to find the highest populations of aphids. Concentrate on field edges particularly where celery fields border harvested lettuce fields. Use at planting in fields that have a history of aphid infestations. The rate applied affects the length of control. Use higher rates where infestations occur later in crop development or where pest pressure is continuous.