Seasonal abundance of insects associated with feverfew, St. John's wort, valerian, and echinacea was determined under field conditions. In the field, feverfew (Tanacetum parthenium), attracted major predators (mainly Geocoris and Orius) of whiteflies and thrips whereas the other medicianl plant species were not as effective in attracting predators. Even without their preferred prey, these predators were still present in feverfew, which suggests that this plant is an important alternative food source.