Controlling

Aphids

in your garden

Controlling

Aphids

In Your garden

Controlling

aphids

In Your Garden

Contents

Download this factsheet

CONTROL APHIDS IN YOUR HOME WITH THESE ECO-FRIENDLY PRODUCTS

Encapsulated fertilizer

Osmocote

 

Horticultural oil sprays

Mineral oil: Bonide All Seasons Horticultural and Dormant Spray Oil; Monterey Horticultural Oil, Summit Year Round Spray Oil

Insecticidal soaps

Bayer Advanced Natria Insecticidal Soap, Bonide Insecticidal Soap, Miracle-Gro Nature’s Care Insecticidal Soap, Garden Safe Insecticidal Soap, Safer Brand Insect Killing Soap

Insecticidal soaps with pyrethrins

Safer Brand Tomato and Vegetable Insect Killer, Safer Brand Yard and Garden Insect Killer

Sticky barriers

Stikem Tree Pest Barrier, Tree Tanglefoot Insect Barrier

Physical controls

Bug Blaster

Row covers (Fast Start Seed Blanket, Easy Gardener Plant and Seed Blanket, Harvest Guard Protective Garden Cover, Turf Starter Seed Germination Blanket, others)

Beneficial insects

Green lacewings, lacewing eggs, lady beetles (ladybugs): available at local garden centers or online

All aphids make honeydew, a sweet, sticky substance on leaves and stems that attracts ants. Argentine ants love honeydew so much that they protect aphids from their natural enemies. (See the Ant fact sheet in this series for tips on controlling ants.) Honeydew may also cause harmless sooty mold fungus, which makes leaves look black and dirty.

Argentine ants are frequent invaders in California homes. They are tiny (1/8 inch). They come inside a fewat a time at first (the scouts), and then in long lines, fol- lowing scent trails to a food source.

Are those aphids on your plants?

Aphids are very small insects with soft, pear-shaped bodies, often found on young buds, stems, and the underside of leaves. If you look closely you’ll see that they have long legs and antennae. Some have wings. A large infestation can stunt plant growth or distort leaves and flowers.

Aphids aren't all bad...

A few aphids on your plants can actually make your garden healthier because they attract beneficial insects—good bugs that eat pests and pollinate your garden. Many helpful spiders and bugs (like ladybugs, green lacewings, and tiny non-stinging parasitoid wasps) will stay in your garden if there are aphids to eat. Aphid problems often start early in the spring. As the beneficial insects arrive and reproduce in your garden, the aphid population shrinks.
If a large number of aphids seem to be damaging roses and other plants and the beneficials haven’t shown up yet, you can reduce the aphid population with a sharp stream of water from your hose, or a spray with horticultural oil or insecticidal soap (see product list). You can also purchase lady beetles (ladybugs) or green lacewings and release them onto your infested plants.

Attracting beneficial insects to your garden

  • Plant a wide variety of flowering plants. (See the Planting a Healthy Garden fact sheet in this series.) Many aphid-eaters, including tiny wasps and lacewings, feed on pollen and nectar.
  • Buy beneficial insects like green lacewings or ladybugs (see the Eco-friendly Products list on the front page), but wait until aphids have arrived.
  • Keep the ladybugs you buy from leaving your garden. Put them in the fridge for 24 hours. In the evening, mist the aphid-infested plants with water, and shake the ladybugs out of their container onto the wet leaves. In the morning, they will wake up gradually with the warmth of the sun, thirsty and hungry—and in ladybug fast-food heaven.

Controlling aphids

Aphids (and other plant pests including whiteflies and scale) produce a sweet, sticky substance called honeydew that attracts ants. Seeing a lot of ants on plant stems is a sure sign of a pest infestation. Since ants will actually protect honeydew-producers from natural predators, it’s important to keep ants away when you’re trying to get rid of aphids.

  • Wipe off or prune away large numbers of aphids from leaves and buds.
  • Use a strong stream of water to wash off both aphids and honeydew. Do this early in the day so that the plants will dry before hot sun hits and burns the leaves.
  • Paint a sticky barrier, such as Tanglefoot or Stickem (see product list), around the trunks of woody plants, so that ants won’t be able to reach aphids on stems and leaves.
  • Bring on the ladybugs! (See above.)
  • If all else fails, spray with a horticultural oil spray to smother the aphids.
Ants "farming" aphids on a plant stem.
Ants are attracted to the honeydew that aphids make.

Prevent Aphids' Arrival

  • Use slow-release fertilizers. Some aphids reproduce more quickly on plants with high levels of nitrogen in their leaves and buds. Organic and time-release fertilizers slowly release small amounts of nutrients, so new plant growth doesn’t come all at once.
  • Avoid excessive pruning in early spring. Pruning encourages tender new growth that attracts aphids.
  • Use a row cover to block out aphids and other pests but allow air, light, and water to reach plants.
Row cover use dto keep pests out of growing plants in the garden
A row cover will keep aphids away from plants.