ANR-189, Reprinted June 1996. Patricia Cobb, former Extension Entomologist

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Controlling Aphids on Ornamentals

Aphids, or plant lice, belong to a large group of insects that suck sap from a wide variety of plants. Aphids may be found in large numbers, with winged and wingless forms often present at the same time. Although aphids are common prey for many parasites and predators, their tremendous reproductive potential allows their numbers to increase very quickly.

Wingless aphids covering rose stem

Description

Aphids are small, soft-bodied, pear-shaped insects that often possess a pair of hornlike structures known as cornicles at the posterior end of the abdomen. Winged forms have wings held vertically above the body when at rest. Aphids vary in color; some are green, others pink, yellow, or black. Some species are covered with white waxy fibers that give them a cottony appearance. Aphids excrete honeydew, which consists of excess sugars and water.

Life History

The life cycle of most aphids is complex. Most species overwinter as eggs. In the spring, these eggs hatch into females that produce living young without mating. Several generations of wingless aphids may be produced in this way. Later in the season, winged forms appear and migrate to different host plants. Late in the season, aphids move back to the original host, and a generation of males and females is produced. These aphids mate, and the eggs that are produced overwinter. These methods of reproduction enable aphid numbers to build rapidly over a short period of time.

Damage

Aphids damage a wide variety of plants, including row crops, fruit trees, and ornamentals. Damage occurs to plants as the aphids pierce the tissue with needlelike mouthparts and suck out the sap. Leaf-feeding aphids may cause leaves to become deformed when heavy infestation occurs. Plants are generally weakened by aphid feeding. Some aphid species spread diseases from one plant to others.

Honeydew produced by aphids is an ideal medium for the growth of sooty mold. This mold gives plants infested with aphids a dirty, sooty appearance and may further weaken the plant by reducing its photosynthetic processes.

Woody alder aphids on maple leaf. Note cottony appearance.

Control

Since aphid numbers build rapidly, frequent and thorough inspection of plants is essential. This will help determine the proper treatment method.

Natural parasites and predators help reduce aphid populations when they first begin to build in the spring. To avoid destroying these natural controls, delay treating with an insecticide as long as possible. Instead, wash off aphids with a forceful stream of water; shake smaller plants after washing them. Use the water treatment early or late in the day to avoid sunscald on plants.

Use an insecticide as a last resort--when inspection reveals a large buildup of aphids. Retreatment may be necessary late in the season when winged aphids move from plant to plant. Late summer to early fall treatment destroys egg-laying females of some species and thus reduces the number of overwintering eggs.

Aphid problems have increased in Alabama nurseries and greenhouses. Primary pests are the green peach and melon aphids, which have developed pesticide resistance due to repeated heavy use of insecticides. Presently, cultural practices and rotation of insecticides are important in suppressing aphid problems.

Frequent inspection of plant material is essential to prevent rapid buildup of aphids in nurseries and greenhouses. In addition, new plant material should be inspected for aphids before it is established. Cleanup of plant dumping sites, escaped plants under benches, and weeds outside greenhouses or adjacent to nursery stock can help to reduce the likelihood of aphids in growing areas.

The insecticides listed in Table 1 are recommended for homeowner use for aphid control on outdoor ornamentals. Table 2 lists insecticides recommended for commercial use in nurseries and greenhouses.

 Table 1. Homeowner Use.

Chemical	Amount To Use Per Gallon Of Water
acephate ORTHENE 15.6%EC	1 tablespoon
diazinon 12.5% EC SPECTRACIDE 25% EC	4 teaspoons 2 teaspoons
dimethoate CYGON 2E	2 teaspoons
insecticidal oil insecticidal concentrate ("soap")	See label. See label.
malathion 57% EC	2 teaspoons
Note: EC or E = emulsifiable concentrate

 Table 2. Commercial Use.*

Chemical	Rate
acephate ORTHENE TT&O SPRAY 97 1300 ORTHENE TR	See label.
azadirachtin AZATIN 3.0 XL NEEMAZAD 4.5 EC	See label.
Beauveria bassiana BOTANIGARD ES NATURALIS-O	See label. Wait 48 hours before applying fungicides.
bendiocarb DYCARB 76WP FICAM 76WP TURCAM 76WP	See label.
bifenthrin ATTAIN TR TALSTAR GH	See label.
chlorpyrifos DURAGUARD 20 ME DURAPLEX TR	See label. Do not use Duraguard on kalanchoes
cyfluthrin DECATHLON 20WP DURAPLEX TR TEMPO 2 TEMPO 20 WP	See label.
diazinon KNOX-OUT 23EC	12-25 oz./25 gal
dimethoate CYGON 2E	See label. See plant use list on label. DO NOT use on crape myrtle or Burford or Chinese hollies.
dichlorvos VAPONA	See label.
endosulfan THIODAN INSECTICIDAL SMOKE THIODAN 50WP THIODAN EC	See label.
fenoxycarb PRECISION 25 WP PRECLUDE TR	See label.
fenpropathrin TAME 2.4EC	See label.
fluvalinate MAVRIK 2F	See label.
horticultural oil SUNSPRAY ULTRA FINE	See label. See label for additional application information.
imidacloprid MARATHON 1%G MARATHON 60 WP Merit 75 WP	See label.
insecticidal soap M-PEDE OLYMPIC INSECTICIDAL SOAP	See label.
kinoprene ENSTAR II SC	See label.
lamda-cyhalothrin TOPCIDE	.3-1.2 oz/25 gal
malathion MALATHION 57EC	See label.
methiocarb MESUROL 75W	See label. Methiocarb is a RESTRICTED USE pesticide.
Clarified Hydrophobic Extract of Neem Oil TRIACT 70	See label.
naled DIBROM formulations	See label.
nicotine Fulex Nicotine Plant Products Nicotine	See label. Nicotine is a RESTRICTED USE pesticide.
permethrin ASTRO	See label.
Pymetrozine ENDEAVOR	See label.
pyrethrum NATURAL PLUS PYRENONE X-CLUDE 1100 PYRETHRUM TR	See label.
sulfotepp DITHIONO PLANTFUME 103	See label. Sulfotepp is a RESTRICTED USE pesticide.
*Always check the product label for phytotoxicity information. See label for site use.

Use pesticides only according to the directions on the label. Follow all directions, precautions, and restrictions that are listed. Do not use pesticides on plants that are not listed on the label.

The pesticide rates in this publication are recommended only if they are registered with the Environmental Protection Agency or the Alabama Department of Agriculture and Industries. If a registration is changed or cancelled, the rate listed here is no longer recommended. Before you apply any pesticide, check with your county Extension agent for the latest information.

Trade names are used only to give specific information. The Alabama Cooperative Extension System does not endorse or guarantee any product and does not recommend one product instead of another that might be similar.

For more information, contact your county Extension office. Look in your telephone directory under your county's name to find the number.