Aphids are little suckers

KENNEWICK -- One insect pest plaguing area gardens are aphids.

These little suckers must have been awaiting spring just as much as area gardeners. I can imagine them perched next to buds just before new growth emerged, hungrily drooling with wicked smiles on their little faces.

Yes, aphids are little suckers. They have piercing-sucking mouthparts that allow them to pierce plant tissues and tap into sap containing sugars and amino acids.

Because the sap is high in sugar content and low in amino acids, the aphids must process large amounts of sap to get the nitrogen they need from the amino acids. They're not able to utilize all the sugar, so they excrete it as honeydew, a sugary liquid. It's this "honeydew" excrement that leads to sticky plant leaves and "drippy" trees.

In addition to sucking on plant sap, some aphids also inject toxins into the plant tissues on which they are feeding. These toxins cause curled leaves, stunted, and abnormal growth.

It's amazing how quickly aphids can multiply and become a problem on plants. In just a few weeks a few aphids can become a big problem.

Let's do the math with just one wingless adult female aphid. She is capable of producing 40 to 60 babies. These "babies" mature quickly and in seven to 10 days and then start producing baby aphids of their own. In the short span of a few weeks, a dozen aphids can develop into an infestation of thousands of aphids.

Prevent aphids from becoming a big problem by inspecting plants and employing control strategies before their population explodes and causes significant damage to your plants. There are both non-chemical and chemical ways to control aphids:

1. One of the simplest ways to discourage aphids is with a forceful spray of water. Periodic spraying will knock off and kill a number of aphids.

2. Recognize and encourage predators. I've already seen ladybird beetle (aka ladybugs) adults and larvae, syrphid fly (aka hover flies) larvae and lacewings at work eating aphids. To protect these beneficial insects, only use "soft" insecticides (such as insecticidal soaps and horticultural oils) that will kill aphids, but leave the beneficial aphid-eating insects alive.

3. There are a number of insecticides on the market that will effectively kill aphids. Some work by direct contact with the aphids. These materials must be sprayed directly on the aphid's body to be effective. If you use a contact insecticide, keep in mind that most aphids are found on the undersides of the leaves, so be sure to spray the bottoms of leaves too.

Systemic insecticides are sprayed on the leaves and taken into the plant sap, poisoning the aphids as they feed.

Some systemics are applied early in the season as a drench to the soil and taken up into the plant by the roots.

Systemics applied to the leaves are particularly effective when leaves have already curled around the feeding aphids, protecting them from contact sprays.

Before you buy or use an aphid control product, read the label to make sure it can be used on the type of plant where you have an aphid problem.

Many systemic insecticides can't be used on vegetable or fruit crops.

* Marianne C. Ophardt is a horticulturist for the Washington State University Extension Office in Benton County.

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