However, large populations can turn leaves yellow and stunt shoots aphids can also produce large quantities of a sticky exudate known as honeydew, which often turns black with the growth of a sooty mold fungus. Low to moderate numbers of leaf-feeding aphids aren't usually damaging in gardens or on trees. Because each adult aphid can produce up to 80 offspring in a matter of a week, aphid populations can increase with great speed. When the weather is warm, many species of aphids can develop from newborn nymph to reproducing adult in seven to eight days. In some cases, aphids lay these eggs on an alternative host, usually a perennial plant, for winter survival. Some species produce sexual forms that mate and produce eggs in fall or winter, providing a more hardy stage to survive harsh weather and the absence of foliage on deciduous plants. They molt, shedding their skin about four times before becoming adults. Most aphids in California's mild climate reproduce asexually throughout most or all of the year with adult females giving birth to live offspring-often as many as 12 per day-without mating. LIFE CYCLEĪphids have many generations a year. Unlike leafhoppers, plant bugs, and certain other insects that might be confused with them, most aphids don't move rapidly when disturbed. The ability to produce winged individuals provides the pest with a way to disperse to other plants when the quality of the food source deteriorates.Īlthough they may be found singly, aphids often feed in dense groups on leaves or stems. Generally adult aphids are wingless, but most species also occur in winged forms, especially when populations are high or during spring and fall. The presence of cornicles distinguishes aphids from all other insects. Most species have a pair of tubelike structures called cornicles projecting backward out of the hind end of their body. A few species appear waxy or woolly due to the secretion of a waxy white or gray substance over their body surface. IDENTIFICATIONĪphids have soft pear-shaped bodies with long legs and antennae and may be green, yellow, brown, red, or black depending on the species and the plants they feed on. Many aphid species are difficult to distinguish from one another however, management of most aphid species is similar. Almost every plant has one or more aphid species that occasionally feed on it. The parasitic wasp (center) has emerged from the circular hole in the top left mummy.Īphids are small, soft-bodied insects with long slender mouthparts that they use to pierce stems, leaves, and other tender plant parts and suck out fluids. Mummified aphid bodies indicate that they have been parasitized.
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