The most common aphids in Florida citrus are the green citrus aphid (Aphis spiraecola), the cotton or melon aphid (A. gossypii), and the brown citrus aphid (Toxoptera citricida). Brown citrus aphid is particularly important as a vector of citrus tristeza virus. Aphids are dependent on the availability of newly expanding leaves for their development and reproduction, so these insects may be problems during periods of new citrus growth, primarily spring and fall. Aphids are largely controlled by many generalist natural enemies such as ladybeetles, hoverflies, and lacewings, that normally maintain their populations, and those of other flush-feeding insects, below levels that warrant treatment in producing groves. Excessive honeydew accumulation on leaves will result in the growth of sooty mold fungus that blocks light and reduces photosynthetic activity. However, mature groves sustain little damage and should not need treatment. Treatment is warranted only in young groves (< 3 yrs old) if a large portion (i.e. > 50%) of expanding terminals is infested. Surveys for aphids should be conducted early in flushing cycles when most terminals are still in the feather stage. Systemic materials, such as Temik or Admire, applied to the soil will give good control with minimal impact on beneficial species, but the time required for uptake of these materials by the tree restricts their usefulness as preventive, rather than responsive, treatments.