The story behind all this begins when a tiny wasp inserts an egg into the aphid. In about two days a wasp grub hatches and feeds on the living aphid by osmosis for about six to eight days, killing the aphid.
During this time the larva expands in size so that the aphid's body swells, giving it a bloated appearance. The larva cuts a slit in the bottom of the aphid, and, working from inside the aphid, attaches the dead aphid to the leaf with silk and glue.
Then the wasp grub still inside the mummy molts to the pupal stage as the dead aphid turns from green to brown, becoming a "mummy. At the right, a black wasp emerges from a mummy's rear end. In spring an egg hatches, producing a wingless female aphid who soon begins parthenogenetically producing new wingless females. Generation after generation of wingless females survive one another until hot weather comes or maybe the plant on which they are living dies and then suddenly some of the females grow wings and fly off.
At the left you see what a winged aphid may look like, though they come in many colors and shapes. This new generation of female winged aphid very well may at this time find a plant host of a completely different species from that on which their spring generations developed.
For instance, Green Peach Aphids overwinter as eggs on peach and related trees but in spring they move to various weeds and agricultural crops, and then still later they move onto potato crops, only in the fall returning to peach and related trees.
Typically late in the year when it's time to move back to the plant species on which the aphid overwinters, finally some aphids develop into males as well as females. Sexual reproduction then takes place and when the mated females return to the winter plant-host they lay fertilized eggs. While these materials may kill higher numbers of aphids than soaps and oils, their use should be limited, because they also kill the natural enemies that provide long-term control of aphids and other pests, and they are associated with bee kills and environmental problems.
Repeated applications of these materials may also result in resistance to the material. Insecticides such as oils and soaps are also safer to use when children and pets may be present. Formulations combining insecticidal soaps and pyrethrins may provide slightly more knockdown than soaps alone yet have fewer negative impacts on natural enemies than malathion, permethrin, and acephate, because pyrethrins break down very quickly.
Systemic insecticides are also available for aphid management, primarily for woody ornamentals. These materials, including imidacloprid, are very effective and are especially useful for serious infestations of aphids such as the woolly hackberry aphid, which is often not effectively controlled by biological control or less toxic insecticides. Imidacloprid can have negative impacts on predators, parasitoids, and pollinators, so its use should be avoided where soaps and oils will provide adequate control.
To protect pollinators, don't apply imidacloprid or other systemic insecticides to plants in bloom or prior to bloom. Home-use soil-applied imidacloprid products are often diluted with water in a bucket and poured around the base of the tree or plant.
Professional applicators can use soil injectors, which provide better control with less runoff potential. Applications are usually made in spring when aphids first become apparent. Adequate rain or irrigation is required to move the product through the soil to the roots and up into large trees, and it may take several weeks to see an effect on aphids feeding on leaves.
One application on hackberry is enough to control hackberry woolly aphid for two to three years. All rights reserved. For noncommercial purposes only, any Web site may link directly to this page. Unfortunately, we cannot provide individual solutions to specific pest problems.
See our Home page , or in the U. Agriculture and Natural Resources, University of California. Wingless adults and nymphs of the potato aphid. Woolly apple aphid adults showing waxy coating. Some aphids overwinter as eggs such as the mealy plum aphid on plums. Sooty mold, growing on honeydew produced by the hackberry woolly aphid. Leaf curling caused by rosy apple aphid.
Identification Life cycle Damage Management. About Pest Notes Publication Glossary. Bean aphid. Cabbage aphid. Green peach aphid. Peppers, spinach, tomato, cucurbits, carrot, lettuce, legumes, corn, flowers, flowering plum, and stone fruit. Melon cotton aphid. Potato aphid. Green apple aphid. Leaf curl plum aphid. Mealy plum aphid. Rosy apple aphid. Woolly apple aphid. Ash leaf curl aphid. Crapemyrtle aphid.
Giant conifer aphid. Hackberry woolly aphid. Oleander aphid. Create a personalised ads profile. Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Share Flipboard Email. Debbie Hadley. Entomology Expert.
Debbie Hadley is a science educator with 25 years of experience who has written on science topics for over a decade. Updated March 07, Featured Video. Cite this Article Format. This allows them to stay hydrated during hot or dry periods.
Ladybird feeding on an aphid. A generation of aphids survives the winter as eggs, which allows them to withstand extreme environmental conditions of temperature and moisture. In spring the eggs on the plant primary host hatch, leading to the first generation of aphids.
All the aphids born from the winter eggs are females. Several more generations of female aphids are born during the spring and summer. A female can live for 25 days, during which time she can produce up to 80 new aphids. Spring and summer reproduction occurs asexually — without males.
In these cases, the resulting aphids are basically clones of the mother. In addition, the young are born live rather than as eggs. When the fall approaches, there is a generation that grow into both male and female individuals.
Females fertilized by the males lay winter eggs on the plant where they are, closing the cycle. Aphids can be winged or wingless. Usually the first generation to emerge from the winter egg are wingless. However, after several generations there can be a lack of space on the host plant.
This triggers the birth of a generation of winged aphids, which can migrate to other hosts. Some species of aphid develop only on plants of a particular species.
These types of aphids are called monoecius. The most common species that attack crops are heteroecious aphids. Heteroecious means that they feed on different plant species. Heteroecious aphids that reproduce sexually at least once in their lives start their cycle when the winter eggs hatch on the primary host.
The primary hosts are usually annual weeds, shrubs or trees. A couple of parthenocarpic generations reproduced without fertilization then give rise to a generation of winged females that migrate to the secondary host. This is usually a cultivated plant.
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