Andre CampbellWoolly aphids look like small patches of white cotton on a plant. You may find them on leaves, stems, or branches. Some species also feed on roots.
If you want to know how to get rid of woolly aphids, first check how many you see and whether the plant is growing well.
A few on a healthy tree may cause little harm. Pay closer attention to young trees, especially young apple trees [1].
How to Identify Woolly Aphids
Woolly aphids are small insects covered in white, waxy fluff. They often gather in groups.
Gently brush aside some of the fluff to look for the insects beneath it. Other pests, such as mealybugs, can also look white and fuzzy.
There are several kinds of woolly aphids, and they do not all feed on the same plants.
Woolly apple aphids, for example, can feed on apple trees, cotoneaster, and pyracantha. They may cause bumpy growths on apple branches or roots.
Heavy feeding on the roots can slow the growth of a young apple tree [1, 2].
How to Control Woolly Aphids Naturally
You may only need to watch a small group of aphids. If their numbers grow or the plant is being harmed, try the steps that fit your situation.
1. Wipe Off Small Groups
If you can reach the aphids, wipe them off a sturdy stem with a damp cloth or a soft brush. Take care around tender new growth.
Check the spot again a few days later. More aphids may appear.
2. Spray Them With Water
A firm stream of water can knock aphids off a small plant or a low branch. Aim at the group of insects, and lower the water pressure if the stem bends or breaks.
Water cannot reach aphids hidden inside curled leaves or feeding on roots [2, 3].
3. Remove a Badly Infested Twig
If aphids cover just one small twig, you may be able to cut it off. Put the twig in the trash.
Prune only if you can remove the twig without harming the plant. Cutting off a twig will not remove aphids elsewhere on the tree or on its roots.
4. Use Garden Insecticidal Soap
Insecticidal soap may help control woolly aphids that it touches.
Choose a product labeled for the plant you want to treat. Spray the infested areas well and follow the label for any repeat treatment.
The aphids’ waxy covering makes them hard to reach, so the spray may only reduce their numbers. Do not replace garden insecticidal soap with a homemade dish soap mix.
5. Try a Labeled Horticultural Oil
Horticultural oil may also reduce woolly aphids on leaves and branches. Some garden oil products are made from neem.
Check that the product is labeled for your plant. Follow its directions for mixing and spraying, including any limits for hot weather.
The oil must reach the aphids; spraying the branches will not treat aphids on the roots.
6. Give Parasitic Wasps Time to Work
Tiny parasitic wasps can help control woolly aphids above ground. One called Aphelinus mali attacks woolly apple aphids.
An aphid attacked by this wasp may turn into a dark, puffy shell. If you see these shells and the plant is growing well, keep watching before you decide to spray [2].
7. Protect Lady Beetles
Lady beetles, also called ladybugs, eat woolly aphids. Their young eat aphids too.
Look for these helpful insects before treating a plant. They may already be bringing the aphid numbers down.
8. Grow Flowers for Hoverflies
Adult hoverflies visit flowers. Their young can eat woolly aphids on parts of a plant above ground.
Grow a mix of flowers near your garden to welcome hoverflies. Flowers give the adults a reason to visit, though they do not guarantee that hoverfly young will appear on an infested plant.
9. Leave Green Lacewings to Feed
Young green lacewings feed on woolly aphids. If you spot them near an aphid group, leave them to hunt.
Like other helpful insects, they can reach aphids on exposed plant parts. They cannot reach aphids living on the roots [1].
10. Avoid Sprays That Kill Many Kinds of Insects
Sprays that kill many kinds of insects may also kill the wasps, lady beetles, hoverflies, and lacewings that eat aphids. Losing these helpers can make an aphid problem worse.
If you need a spray, use it only where needed and follow its label. Check for helpful insects first [4].
11. Keep Checking the Plant
Look at the plant every few days to see whether the aphid groups are growing or shrinking.
Check whether new growth looks healthy. Water the plant when it needs it, and avoid giving it more fertilizer than it needs.
If a young apple tree is growing poorly and has woolly aphids near its base, aphids may also be feeding on its roots. The sprays listed above will not reach them there.
Takeaway
Most woolly aphids do not pose a serious threat to a healthy tree. For a small group you can reach, try wiping it off or using water. Helpful insects may also keep the aphids in check.
If the plant is struggling, look closely at where the aphids are feeding. Soaps and oils may reduce aphids they touch above ground, but they will not treat aphids on the roots.
Sasha Campbell
I started treating Wooly Aphids on my strawberry plants, grown in a small indoor green house under LEDS. I used soap mixture, Gin (alcoholic beverage mixed with soap), and alcohol diluted in water. I used a direct application with Q-tip/ artist brush, and general spray. I also used a consumer product GARDEN SAFE with pyrethrins. All of these in rotation for about 10 weeks. I could not control them and ended up ripping out all the plants (strawberry and tomato). These Wooly Aphids are really tough to control indoors and organically…
I haven’t had much success with NEEM oil as it doesn’t mix well unless heated. Are there methods of mixing NEEM oil in water so the neem doesn’t solidify on the sides of the spray bottle?
Yes — that’s a common problem with neem oil, especially in cooler temperatures. Neem oil hardens when cold, so always mix it with lukewarm water. Also, oil and water don’t mix naturally, so you need something to help them combine. Add an emulsifier like a mild liquid soap.
However, even with an emulsifier, neem oil can start to separate after a while, so shake the bottle vigorously before each use to keep the solution well blended.