Test Your Knowledge - April

A Test Your Knowledge Unknown
Aphids on an iris bud
Millie Davenport, ©2006 HGIC, Clemson Extension

Yes. These are aphids!

Aphids are small, soft-bodied, pear-shaped insects that measure 1/16 to 3/8 inch. There are several species of aphids. Depending on species, they can range in color from tan, pink, or green to almost black and may or may not have wings. Aphids feed on leaves and stems by piercing the plant tissue and sucking plant sap. Their feeding can cause leaves to curl or become distorted. In addition, aphids sometimes serve as vectors to transmit plant viruses which may result in disease development. The first sign of aphids being present is usually a sticky residue left on leaves. The aphids excrete a sticky substance called honeydew as they feed. The honeydew will land on any surface beneath the feeding area, such as leaves, branches, understory plants or even cars and concrete surfaces. Sooty mold is a fungus that grows on the sticky surface of the honeydew. As the sooty mold grows it will form a black, powdery or velvety coating on leaves and other areas where the honeydew landed. The good news is that sooty mold does not infect the plant tissue. For more information on sooty mold, see HGIC Hot Topic July 2008.

Prevention & Treatment: Aphids have several natural enemies, such as lady beetles, lacewings, syrphid flies, damsel bugs and wasps. Since the use of insecticides will also kill beneficial insects, it is best to try to first allow the beneficial insects to reduce the aphid population. The following images can be used to help identify the beneficial insects in the landscape. For more information on these insects, see EIIS/BB-1, Beneficial Insects and Related Arthropods (http://entweb.clemson.edu/eiis/pdfs/bb1.pdf).

Lady beetle larva feeding on aphids
Lady beetle larva feeding on aphids, size 3/8″ long.
Clemson University - Pat Zungoli, USDA Cooperative Extension Slide Series, Bugwood.org

Lady beetle adult
Lady beetle adult, size ¼″ long.
Frank Peairs, Colorado State University, Bugwood.org

Lacewing larva feeding on aphids
Lacewing larva feeding on aphids, size ¼″ long.
David Cappaert, Michigan State University, Bugwood.org

Brown lacewing adult
Brown lacewing adult, size ¾″ long.
Joseph Berger, Bugwood.org

Green lacewing adult
Green lacewing adult, size ¾″ long.
Frank Peairs, Colorado State University, Bugwood.org

Syrphid fly larva feeding on aphids
Syrphid fly larva feeding on aphids, size ½″ long.
Whitney Cranshaw, Colorado State University, Bugwood.org

Syrphid fly adult
Syrphid fly adult, size ½″ long.
Whitney Cranshaw, Colorado State University, Bugwood.org

Damsel bug adult
Damsel bug adult, size ¼″ long.
Bradley Higbee, Paramount Farming, Bugwood.org

If necessary, insecticidal soap (such as Safer Insecticidal Soap or Concern Insect Killing Soap) can be used to reduce the aphid population. Keep in mind that the insecticidal soap must be sprayed directly on the aphid to be effective, so be sure to coat the under and upper side of the leaves and stems. Some plants are sensitive to insecticidal soaps. For more information see, HGIC 2771, Insecticidal Soaps for Garden Pest Control. For additional information on how to control aphids contact the Home & Garden Information at its toll-free number, 1-888-656-9988 (9 am to 1 pm, M-F).

For more information on aphids, see:

HGIC 2001, Apple & Crabapple Insects
HGIC 2002, Crape Myrtle Diseases & Insect Pests
HGIC 2057, Viburnum Diseases & Insect Pests
HGIC 2101, Chrysanthemum Diseases & Insect Pests
HGIC 2102, Daylily Diseases & Insect Pests
HGIC 2104, Flowering Bulb Insect Pests
HGIC 2105, Pansy Diseases & Insect Pests
HGIC 2107, Rose Insects & Related Pests
HGIC 2201, Bean & Southern Pea Insect Pests
HGIC 2203, Cabbage, Broccoli & Other Cole Crop Insect Pests
HGIC 2205, Insect Pests of Sweet Corn
HGIC 2207, Cucumber, Squash, Melon & Other Cucurbit Insect Pests
HGIC 2218, Tomato Insect Pests
HGIC 2252, Common Houseplant Insects & Related Pests

Millie Davenport
Home & Garden Information Center

Page maintained by: Home & Garden Information Center

This information is supplied with the understanding that no discrimination is intended and no endorsement by the Clemson University Cooperative Extension Service is implied. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.