On mature trees, such as in citrus orchards, aphids and the honeydew they produce can provide a valuable food source for beneficial insects. Consider the nonchemical controls discussed below, as most insecticides will destroy beneficial insects along with the pest. MANAGEMENTĪlthough aphids seldom kill a mature plant, the damage they do and unsightly honeydew they generate sometimes warrant control. Heavy infestations of crown and root aphids on carrots may weaken tops, causing them to tear off when carrots are harvested. The woolly apple aphid infests woody parts of apple roots and limbs, often near pruning wounds, and can cause overall tree decline if roots are infested for several years. In fall, this species often moves to poplar trees, where it overwinters in the egg stage and produces leaf galls in spring. The lettuce root aphid is a soil dweller that attacks lettuce roots in spring and summer, causing lettuce plants to wilt and occasionally die. Although losses can be great, they are difficult to prevent by controlling aphids, because infection occurs even when aphid numbers are very low it takes only a few minutes for the aphid to transmit the virus, while it takes a much longer time to kill the aphid with an insecticide.Ī few aphid species attack parts of plants other than leaves and shoots. The viruses mottle, yellow, or curl leaves and stunt plant growth. Squash, cucumber, pumpkin, melon, bean, potato, lettuce, beet, chard, and bok choy are crops that often have aphid-transmitted viruses associated with them. A few species cause gall formations.Īphids may transmit viruses from plant to plant on certain vegetable and ornamental plants. Some aphid species inject a toxin into plants, which causes leaves to curl and further distorts growth. 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.
#WOOLY APHIDS ON SPANISH BROOM SKIN#
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.
0 kommentar(er)
