Aphids

Also known as Plant Lice or Greenflies

Description

Aphids are insects measuring 1/16 - 1/8 inch. They have pear-shaped bodies with long antennae and legs. You may see wings on them, though not all Aphids have them. They come in various colors, including black, brown and green. You may also see red or pink Aphids. Aphids tend to cluster on the undersides of leaves, especially on the younger, smaller leaves of the crown, where they feed on the juices of African Violets. If untreated, Aphids can cause a lot of damage to your plant, eventually leading to its demise. The danger of Aphids is compounded by the fact that many Aphids carry viruses.

Distinguishing Symptoms

• Leaves have honeydew on them. Honeydew is a shiny, sticky substance left behind by certain insects. Honeydew will often host a thin, black fungus called Sooty Mold. Other insects which leave behind honeydew include Scale and Whiteflies. These two insects, however, are easily distinguished by their physical characteristics. (Note: Do not mistake the honeydew left by Aphids and other insects with the mucus trail left by Snails and Slugs.)
• Visible insects. Look for visible insects clustered particularly on the undersides of the leaves. Aphids are tiny insects, though easily visible. Aphids measure between 1/16 and 1/8 inch in length. They have pear-shaped bodies with long antennae and legs. They may or may not have wings. They come in various colors, including black, brown, green, red and pink.

If your African Violet exhibits these symptoms, it probably has Aphids.

Other Symptoms

• Leaves have a black fungus on them. This is probably Sooty Mold, which finds a host in the honeydew left behind by Aphids and other insects. When Sooty Mold is present, the upperside of the leaves will be covered with tiny, dark speckles.
• Leaves curl up on the edge.
• Leaves pale. They appear yellow or grayish in color.
• Leaves wilt. They may appear translucent brown with a soft, jelly-like consistency.
• Flowers are deformed or twisted.
• Plant growth is slow.

Treatment

First, isolate all infested plants. This will help prevent any further spread of Aphids.

For light infestations, try dabbing the insects with a cotton swab soaked in rubbing alcohol (70 percent isopropyl). Also, use the alcohol to wipe away the honeydew so that Sooty Mold does not set in. If Sooty Mold has already set in, use the alcohol to gently remove it. After cleaning your Violet off with rubbing alcohol, hold the plant upside-down while thoroughly rinsing it with lukewarm water.

For heavier infestations, you may need to treat your Violets with Acephate (as directed on the label) or with Malathion (1 teaspoon of Malathion 50 per 4 liters of lukewarm water). Since Malathion may discolor flowers, Acephate is preferred. Acephate is available in household insect sprays. However, many of these sprays contain a specific additive which may damage the foliage of African Violets. Therefore, if available, use a soluble powder, and mix your own spray.

As an alternative to traditional chemical treatments, try spraying with Neem (Azadirachtin). Neem is a substance which has natural insecticidal properties, and according to currently available research, it is biodegradable and non-toxic. When sprayed on African Violets, it discourages Aphids by making the plant unpalatable. Those Aphids which do continue to feed on the Violet will be rendered incapable of laying eggs. Though Neem does have some systemic effect in plants, spray it as you would other contact insecticides, being sure to cover the undersides of the leaves where Aphids tend to cluster.

Prevention

There is no sure way to prevent Aphids. You can, however, prevent heavy, more costly infestations by simply keeping a watchful eye for the first indications that Aphids are present.

Important Note on the Use of Pesticides

Please note that almost all pesticides are formulated for specific uses and conditions. When applied incorrectly, pesticides can cause ill health or damage to plants. Therefore, when using any kind of pesticide or chemical treatment, always apply as indicated on the product label.

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