Aphids feeding on a rose plant, with their mouthparts inserted into the stem to suck out sap.Īphids feed by inserting their mouthparts into phloem vessels through leaves, buds, stems, or roots and sucking out the sap. Only a few species have a wide range of secondary hosts but these tend to be important pests, such as the green peach aphid. For example, the rosy apple aphid has apple as its primary host and plantain ( Plantago lanceolata) as its secondary host. About 10% of aphid species, however, have a primary woody host where they spend autumn, winter and spring and an unrelated, secondary herbaceous host plant for the summer. Most species of aphids are monophagous or feed on just a few species of closely related plants. Only 25% of all plant species are infested with aphids the aster or sunflower family (Asteraceae), conifers and the rose family (Rosaceae) support the highest number of aphid species. Hibiscus flower infested with aphids and a few mealybugs. In addition to this natural movement, aphids have also been spread by humans, making some species nearly cosmopolitan in their distribution. Several species, such as the English grain aphid, corn leaf aphid, bird-cherry oat aphid and greenbug (as well as some pest leafhoppers and moths) catch a ride on the prevailing winds in the spring to move from southern areas to the Midwest each year. They accomplish this by flying upward to be carried by fast-moving, low level jet streams. These aphids mate and the females lay eggs on the appropriate host plant.Īlthough aphids are generally weak fliers, some species migrate considerable distances.
At the end of the summer, when temperatures begin to drop and daylength decreases, both males and females are produced. These winged females fly to new host plants and produce many more generations of wingless females. A winged aphid.Īfter several generations, when the food supply becomes short or the area becomes overcrowded, winged females (alates) appear. Obviously this doesn’t happen, since natural controls – such as weather and predators – eliminate significant numbers of aphids. Under ideal conditions, one aphid could theoretically produce billions of offspring by the end of a growing season. This “telescoping of generations” means aphids can build up immense populations very quickly. Photo from Įggs within these females start to develop long before birth so that a newly born aphid can contain within herself not only the developing embryos of her daughters but also those of her granddaughters which are developing within her daughters. The nymphs mature and can produce offspring within a week when temperatures are high. The nymphs look like the adults but are smaller. Each female aphid reproduces for a period of 20–30 days, giving birth to 60–100 live nymphs. When these hatch in the spring, they produce only wingless females that give birth to live young (viviparity without mating = parthenogenetic reproduction). In Wisconsin aphids spend the winter as eggs. The life cycle of most species is rather complex. Photo by Whitney Cranshaw, Colorado State University, Aphids feed on stems, leaves, and even roots! They reproduce rapidly to form colonies or clumps, particularly on new growth. They have sucking mouthparts and feed exclusively on plant sap. Two different species of aphids infesting roots. Some, such as the cabbage aphid or wooly apple aphid, secrete a white or gray waxy substance that covers the body. Cabbage aphid, Brevicoryne brassicae, on red cabbage. Many species have two color types, such as the green peach aphid, which has both a green and a red form. Many species are green but others are white, yellow, red (pink), brown, black, or mottled. All aphids have cornicles at the end of the abdomen. Their pear-shaped bodies have “exhaust pipes” (cornicles) protruding from the back end of the abdomen (used to exude droplets of a quick-hardening defensive fluid called cornicle wax). Most aphids are about 1/8 inch long and all are soft-bodied. Aphids are common soft-bodied insects that can be many different colors.Īphids are primarily northern temperate zone insects all in the family Aphididae of the order Hemiptera, with about 1,350 species in North America (5,000 worldwide), although only a handful are considered serious pests.
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