Aphids commonly occur as pests on chrysanthemums and carnations as well as on many other plants grown in plastic or glass houses in California. They are usually found in colonies on plant tips, shoots of new growth, or flowers. Aphids multiply so rapidly under favorable conditions that a light infestation may increase to alarming proportions in a week. They are generally more numerous during cooler months when the most serious damage occurs. However, damage can be observed throughout the year.