Garden Pest Guide: Aphids, Scale & Whiteflies

Recently, my husband pointed out that our small apple tree in North Carolina didn’t look quite right. When I took a closer look, I noticed the new growth at the tips of the leaf buds were curled and distorted and there were several ants running around in the area. On further inspection, I saw aphids, which explains why the ants were there - they tend the aphids for the honeydew they excrete.

Aphids on an apple leaf

How I Treat Aphids

The way I deal with aphids is with soapy water. I mixed a tablespoon of gentle dish soap in a gallon of water and sprayed it directly on the pests. Aphids have soft bodies and the soap breaks the surface tension, which is harmful to them.

While spraying, I noticed white, cotton-like clusters along the small branches. At first, I thought it was mealy bugs, but it wasn’t—it turned out to be clusters of young scale. As they mature, they spread out over the plant.

The cotton clusters on the branches that turned out to be scale

Managing Scale Effectively

Scale is difficult to manage with pesticides because the shell acts like armor, securing and sheltering them to the plant. In Florida, I use a pesticide with pyrethrin and a non-petroleum oil base, but here in North Carolina, I checked the local garden shop and found several soft (organic) insecticides. I started reading the labels to see which pests they effect, most of them not working on scale (which is why it’s very important to read the label!). Then I found Neem oil, which has scale on the list!

With this pest I’ve used some form of oil like light horticultural oil. Oils adhere to and smother the pest. I tend to like Neem oil or the addition of pyrethrin to the horticultural oils for added strength.

Why Proper Identification Matters

For friends who ask me about pest and disease problems, I always say: I need to know exactly what you’re dealing with before I can give advice. If I could see the plant in person, it’d be much easier. Pictures don’t always show what’s really happening—like the apple tree, where the cottony area needed a hands-on look to figure out the problem. If you’re unsure, I recommend contacting your local extension office. They’re there to help (and it’s free), or you can find a good nursery that knows your area and can offer advice.

When Multiple Pest Problems Appear

Sometimes, you’ll see multiple issues at once. A friend in South Florida sent me pictures of tomatoes and peppers with various problems—aphids, thrips, and whiteflies, all at once. When a plant is attacked, it gets weaker and more vulnerable to other problems.

You have to address pest problems early and be diligent to make sure populations do not increase. Once the populations become high, depending on the pest, it can become impossible to get them under control for that season.

Common Garden Pests: Aphids & Whiteflies

Aphids and whiteflies are very common pests. Here’s some info about each of them:

Aphids: These are piercing, sucking bugs. They’re born pregnant and can start reproducing within days, especially in warm weather. They hide in new growth and can escape pesticides in these protected areas. You have to be persistent—soft insecticides can control them if you stay on top of it.

Whiteflies: Another piercing, sucking bug with several stages of growth. Adults have wings and fly from plant to plant. Most pesticides only work on the flying adults. Once the eggs hatch, the young attach under the leaves, protected by their casing. At that stage, only systemic insecticides work, but those can harm pollinators, so I use them only as a last resort. This is why early detection is so important. Then you can still use soft insecticides and avoid the harsher chemicals.

Understanding Sooty Mold

Black sooty mold from pests above

Both aphids and whiteflies tend to live under leaves. Their excrement is called honey dew. This drops onto the foliage beneath them causing what appears to be a black mold. If you see this look at the leaves above it. Chances are you are going to see these pests and usually large populations. You aren’t going to be treating mold (which is a consequence of the insects), but the insects above it.

Final Thoughts on Pest Management

Pest and disease management is a huge topic. The symptoms you see could be from insects or disease, so knowing what you’re looking at is key. Once you figure out what you have, always start with the option least harmful nature—identify beneficial insects, try soft insecticides or oils, and only escalate if you must.

Watch the Process

Guess what? I just happened to make a video of my findings on my apple tree, with an explanation of the bugs and showing you how I get rid of them with my soapy spray!

Check it out here!

Wishing you healthy plants and happy gardening!