ILLINOIS
YARD & GARDEN
  Sap Sucking Aphids
How to identify and safely control aphids
David Robson
Extension Educator, Horticulture, at the Springfield Extension Center, University of Illinois Extension.

Many of the garden insects are a little unusual. For example, scale insects are the one group that shed their legs once they settle down, pierce the plant and create the shell over their body.

False June bugs, a bright iridescent metallic green, will seemingly zoom your face or chest. Actually, you got in the middle of their flight plan and they won’t change.

The male cicada killer will sit in a tree and watch the female struggle for hours to take a cicada (which will be plentiful this year) back to the underground zigzag nest for the hatching eggs to feed on. Insert your own comment about the male cicada killer in here.

Then there are the aphids.

Commonly known as plant lice, they seem to affect every plant from the tallest tree to shortest grass. You’ll find them all over the state, usually peaking during the middle of summer with hot, dry weather.

Aphids may be more difficult to identify, though they are essentially wingless and don’t rapidly move up and down the stem. They look somewhat succulent and fleshy, almost pear-shaped, and about 1/16-inch big.

While there are hundreds of different aphids, it’s easy to identify them.

If they are rosy-colored and on apples, they’re rosy apple aphids. If they are green and on tomatoes, they’re green tomato aphids. You can probably see the pattern here.

What’s interesting about aphids is their life cycle.

Essentially, males are needed once and only once to fertilize the female. In most cases, this is used to create the eggs and only the eggs that hatch. So far, that’s what most insects do.

Aphids vary by hatching once, but continuing to pop out baby aphids without any eggs being fertilized. And every aphid that the female gives birth to is also a female, and already pregnant. So, she’s an immediate grandmother to be.

That’s how the populations build up fast. If you don’t need to find a mate, but can just push out living young without going through the egg hatching stage, you can create armies of yourself in nothing flat.

On the other hand, you’re essentially a clone of your mother, and giving birth to clones of yourself. Therefore, if there’s something just a little wrong, you’re population dies out fast.

Aphids would rather feed than do anything else. Sex, obviously, isn’t on their mind. Eating and birthing is it.

Aphids are sucking insects that feed by thrusting a long beak into plant tissue. As they feed, they withdraw large quantities of sap, often resulting in curling and distortion of leaves. However, they can only digest so much of the sap, and the rest comes out the other end, usually with a little less water and more sugar. Many times, the plants will look distorted and twisted, but sticky and somewhat shiny.

Aphids are usually found feeding on the undersides of leaves or along the stems, out of the sun’s drying heat, or away from preying insects that view them as great food.

As aphids feed, they excrete a sticky substance called honeydew. A sooty black mold often grows in the honeydew and blackens stems and foliage. This fungus is unsightly and is not harmful to the plant, but is annoying to folks with cars, patio furniture or sidewalks under the plant, particularly trees.

Since the aphids are more than likely wingless, they have to use their legs to move around. Therefore, a strong blast of water or a good rain will knock them off the plant and onto the ground where they have to move back up. They usually die before they do.

Insecticidal soaps are another control, and safer than most other chemicals.

 

For more information:

check out the University of Illinois Web site at: www.ipm.uiuc.eduYou can contact David Robson via E-mail: drobson@uiuc.edu

Or write to him in care of:

Illinois Country Living
P.O. Box 3787,
Springfield, IL 62708.

Telephone: (217) 782-6515