A3757-E egetable V GUniversityARDEN of Wisconsin–ExtensionFACTS Vegetable Aphids K. A. Delahaut Aphids, also known as plant lice, Appearance are soft-bodied, sucking . All aphids are soft-bodied and They feed on plant sap and pear-shaped with a pair of corni- excrete a sugary honeydew that cles, or little horns, projecting attracts ants and creates the con- from the rear end of their ditions for sooty mold, a type of abdomens. Adult aphids may or fungus (saprophytic) that feeds may not be winged. Some of the on decaying organic matter. more common species are listed There are several species, below. all belonging to the family , that are capable of attacking any type of vegetation. Aphids that pose the most seri- ous problem to Wisconsin veg- etable production include the green peach, melon and aphids.

Common name Scientific name Description Host plants Bean aphid Aphis fabae Dark green to sooty black Artichoke, , bean, carrot, corn, lettuce, parsnip, rhubarb, spinach, squash. Winter hosts—euonymous & viburnum spp. aphid Brevicoryne brassicae Gray-green with a powdery, Broccoli, Brussels sprouts, cabbage, waxy covering collards, kale, kohlrabi, and radish. Winter host—eggs on host plants. Corn leaf aphid Rhopalosiphum maidis Bluish-green Corn. Winter host—none; migrates from the south. Green peach Myzus persicae Yellowish-green with 3 dark Beet, celery, cole crops, cucurbits, aphid lines on their backs lettuce, pepper, potato, spinach, . Winter hosts—cherry & peach Melon aphid Aphis gossypii Pale yellow to brown or nearly Asparagus, bean, beet, celery, cucurbits, black with black cornicles , spinach. Winter hosts—many. Pea aphid Acyrthosiphon pisum Pale green with black legs Peas. Winter host—alfalfa. Potato aphid euphorbiae Pink or green Asparagus, bean, corn, cucurbits, , lettuce, pepper, potato, sweet potato, tomato. Winter host—rose. GARDEN FACTS University of Wisconsin–Extension Symptoms and effects their reproductive capability. Control Throughout the summer, wingless Reduced plant vigor, stunting and females predominate. However Cultural: Predators such as lady- deformed plant parts are com- winged forms may arise when bird beetle adults and larvae, mon symptoms of aphid infesta- populations become too large for green lacewing larvae, syrphid fly tions. In some cases, it’s the pro- the available food source. In late larvae and several parasitic duction of honeydew or presence summer, in response to the short- wasps all help reduce aphid of sooty mold that alerts the gar- ened daylight hours, wingless numbers. Heavy rains help dis- dener to an aphid outbreak. Most females and males are produced lodge aphids from the plant and, importantly, aphids are excellent for the purpose of mating and during periods of high humidity, transmitters of several viral dis- laying fertilized eggs that will sur- fungal diseases may greatly eases, such as the mosaic virus- vive adverse winter conditions. reduce populations. The remark- es, that cause leaves to shrivel able reproductive capacity of the and that infect a wide range of Scouting suggestions aphid normally overcomes the hosts. In some cases, it’s the effects of natural controls in Look for “hot spots” of aphid appearance of virus symptoms spring when cool temperatures activity scattered throughout the that indicate aphid activity. hinder the development of natural field. Because of the spotty enemies. These natural controls nature of infestations, look for Life cycle most often catch up in the aphids on a number of plants in warmer weather of summer and It is difficult to generalize the life several areas. Examine the termi- fall. cycle of all aphids because of the nals of 15 consecutive plants or diversity of their life habits, which sample units and rate the plants Chemical: Treat crops with an can range from single to multiple as infested or uninfested. Given insecticide when threshold levels hosts. One of the unique charac- the huge reproductive potential of have been reached. One of the teristics of aphids that sets them aphids, an infestation level of problems associated with the apart from all other insects is 5%–10% indicates a potentially control of green peach and their ability to bear live young. damaging infestation. Repeat melon aphids results from their Aphids overwinter as eggs on a checks at weekly intervals to resistance to several insecticides. perennial host. In spring, the determine the need to treat. In particular, aphids have shown eggs hatch and the aphids resistance to organophosphate migrate onto their summer host insecticides. Refer to the when it becomes available. The University of Wisconsin–Extension female aphids can then repro- publication Commercial duce without mating and will hold Vegetable Production in the eggs in their bodies to give Wisconsin (A3422) for a list of birth to live young. By eliminating recommended products. mating and egg laying, aphids have successfully shortened their life cycle and thereby increased

Author: K. A. Delahaut is an outreach specialist with the Integrated Management Program at the University of Wisconsin–Madison and the University of Wisconsin–Extension, Cooperative Extension. Thanks to Jeff Wyman and Phil Pellitteri for reviewing this information. Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, University of Wisconsin–Extension, Cooperative Extension. University of Wisconsin–Extension provides equal opportunities in employment and programming, including Title IX and ADA requirements. If you need this information in an alternative format, contact the Office of Equal Opportunity and Diversity Programs or call Extension Publishing at (608) 262-2655. © 2001 by the Board of Regents of the University of Wisconsin System. Send inquiries about copyright permission to: Director, Cooperative Extension Publishing, 201 Hiram Smith Hall, 1545 Observatory Dr., Madison, WI 53706. To see more Cooperative Extension publications, visit our web site: www.uwex.edu/ces/pubs/ Vegetable Aphids (A3757-E) I-07-2001