It’s the Pest of Times for the Worst of Aphids : Along With Spring’s First Flush of New Growth, You Can Expect Those Little Dickens to Come Feasting on Tender Greenery

Chances are you’ll go into the garden one day soon, if you haven’t already, and find a little army munching on your plants. Along with spring’s flush of new growth in Southern California often come aphids, which consider young, tender foliage a delicacy.

These voracious critters can devour greenery at an alarming rate and are among the most common garden pests. At last count in the United States in the late 1980s, there were 1,350 species of aphids, says entomologist Nick Nisson of the county Agricultural Commission office in Anaheim.

Although you probably envision a little green predator when you think of aphids, there are actually many different colors of aphids found in the back yard. Aphids can be pinkish purple, black, brown, red, white, cream-colored and brilliant yellow. The good news is that only a tiny fraction of aphids are considered pests that will bother plants in your garden, Nisson says.

The type of aphids most commonly encountered in the back-yard garden are small, soft-bodied, stationary insects that congregate at the tips of new growth on plants. If you see a gathering of small insects on young, tender foliage, there’s a good chance they’re aphids, Nisson says.

Some aphids will eat just about any plant, while others are more particular about their meals and stick to certain types of vegetation. During their lifecycle, aphids often change what they are feeding on and will move to different plants as they mature.

Even the pesky aphid types don’t really create a problem if there aren’t too many of them. Aphids can be an important part of a healthy ecosystem, because aphids are food for many “good” insects such as ladybugs and praying mantises, says Geoff Smith, a horticulture instructor at Fullerton College.

Because there are many larger insects that dine on aphids, the aphids fight extinction by reproducing rapidly through parthenogenesis, the development of an egg without fertilization. This process allows aphids to create a population explosion in a short period of time.

Problems occur for the back-yard gardener when aphids multiply unchecked and begin damaging plants. Most aphids feed on plants by piercing tender foliage with a beak and sucking on the plants. Damage from this sucking occurs when the leaves, flowers or fruits mature. The scar tissue the aphids created by sucking when the plant parts were young causes leaves to tightly curl and wrinkle and fruit to become disfigured. While none of this causes long-lasting harm, it can make the plant look unsightly long after the aphids have left, Smith says.

Aphids can also cause serious harm to plants. “Some aphids will carry virus diseases from one plant to another, which can kill plants,” he says.

As they eat, aphids also secrete a honeydew onto plant foliage, which creates problems. A fungus known as sooty mold will begin growing on and eating the honeydew.

“Sooty mold is very unsightly,” says California certified nurseryman and master gardener Bohn Dampier, who works at the Nurseryland Garden Center in San Juan Capistrano. “It looks like you cleaned out your fireplace and threw the ashes on your plant,” he says.

If you notice more than a handful of aphids or sooty mold in your garden, experts suggest dealing with the problem immediately--before the aphids have a chance to take hold and do damage.

Because aphids are generally soft-bodied small insects that often don’t fly, it’s usually fairly easy to get rid of them.

One of the easiest, least expensive ways to deal with them is to spray the plants with a strong blast of water, which should knock the aphids off. You will have to repeat this procedure several times because aphids often spring back. Water is often a chosen method in organic gardening, because it doesn’t harm other friendly organisms such as bumble bees and ladybugs, Smith says.

Other mild alternatives include snipping off affected plant parts and spraying the plants with a soap solution, which you can buy or make by mixing a mild dish-washing soap with water.

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Another nontoxic way to deal with aphids is through the natural process of biological control, which refers to introducing aphid predators such as ladybugs, praying mantises and green lacewings into the garden.

Perhaps the best-known beneficial insect in the garden is the ladybug, which is also known as the ladybird beetle. While most often identified as being red with black dots, ladybugs can be black, gray, red with no spots and black with red spots. One ladybug can eat hundreds of aphids every day, and a ladybug larvae eats even more.

Ladybugs can be purchased at a nursery. It’s best to let them out of their carton at nightfall, because they are less active when temperatures are cooler and more likely to hang around. Let out in the middle of the day, they are more apt to fly away.

The praying mantis is another aphid catcher that can also be purchased at the nursery. They come in egg cases containing hundreds of eggs. Hang the egg casing on a bush and, when the temperatures warm up, hundreds of quarter-inch mantises will hatch. Although they are small when born, they grow quickly. Some people prefer praying mantises to ladybugs, because while ladybugs usually leave the garden once they’re done feasting, praying mantises tend to stick around.

Lacewings can also sometimes be found in the nursery. As adults they eat many pests, including aphids, but lacewings are especially good at eating aphids when they are in the pupal stage, when they are actually called aphid lions.

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If you use any of the above methods and are still plagued by aphids, chances are that you have an army of ants tending to and protecting the aphids.

The Argentine ant, found locally, loves eating the honeydew that aphids produce and will do anything to guard it, including protecting the aphids from ladybugs and lacewings. The ants also enable the aphids to make more honeydew by herding them, much like we herd cattle, from one plant to another. Some ants will even harbor aphid eggs in their nests over the winter to protect them and place them back on plants when the weather warms up, Nisson says.

In order to deal with the ant/aphid connection, you must eliminate the ants’ access to the plants. This can be done by applying a sticky ant barrier to a strip of paper and then encircling the base of the plant, trunk or container with this strip.

Another way to prevent the spread of aphids is to keep weeds in check, because many aphids love fast-growing weeds, which are always full of tender tissue.

Avoiding monoculture planting is another good form of prevention. This refers to growing all of the same crop in a concentrated area. In such a situation, aphids will move rapidly through the entire crop, Smith says. Instead, it is best to interplant with many different plant types, which will tend to stop aphids in their tracks.

Keeping plants healthy is also good protection. Sickly plants are likely aphid targets.