Eliminating Plant Lice: A Guide to Organically Controlling Aphids

Aphids also known as plant lice or greenflies can be one of the most frustrating pests for gardeners to manage. These tiny sap-sucking insects seem to multiply overnight, spreading rapidly to infest both outdoor and indoor plants. With their piercing mouthparts, aphids stunt plant growth and deform leaves, flowers, and fruits. Left unchecked, they will weaken and potentially kill your prized plants.

Though only 1/16 to 1/4 inches long, aphids can quickly colonize plants by the hundreds due to their exceptional ability to reproduce asexually Since you’ll almost always have some aphids flying in from neighboring yards, constant vigilance and control measures are needed to keep them under control

The key is intervening early at the first signs of an infestation, before the population explodes. Once established, the colonies become increasingly harder to eliminate. Luckily, there are several organic and natural methods to get rid of aphids without using harsh pesticides. Here’s how to fight back against these prolific pests.

Recognizing Aphids on Plants

Aphids may be green, yellow, brown, red, or black depending on the species. They tend to feed in large groups on tender new growth, clustered on the undersides of leaves or hiding deep inside plants.

Signs of an aphid infestation:

• Curled, deformed, or yellowing leaves and stunted growth

• Small white “skins” from shed exoskeletons

• Clusters of pear-shaped bugs on stems and the undersides of leaves

• A sticky residue called honeydew left on plants from their waste

• Sooty black mold growing on honeydew deposits

• Ants climbing plants to feed on the honeydew (ants protect aphids)

• Lacewings, ladybugs and other beneficial insects hovering around plants (they feed on aphids)

Closely monitor plants in spring and summer for early aphid invasions. Be sure to check the centermost leaves and new shoots where they like to congregate. Catching infestations when only a few aphids are present makes controlling them much easier.

Organic Ways to Get Rid of Aphids

Avoid using broad spectrum pesticides that will also kill beneficial pollinators and predatory insects that help control aphid populations. Instead, employ these organic solutions that specifically target the plant lice while protecting the rest of your garden ecosystem:

Use Horticultural Oils and Insecticidal Soaps

Insecticidal soaps and oils smother and penetrate soft-bodied insects like aphids on contact. Spray plants thoroughly to coat the undersides of leaves and stems where aphids hide. For best results, apply early in the morning or evening when temperatures are coolest. Repeat applications may be needed.

Apply Diatomaceous Earth

The microscopic razor edges of this powdered chalk-like substance damages the waxy coating on insect bodies, causing dehydration and death. Lightly dust aphid colonies with food-grade diatomaceous earth (DE). Reapply after rain or watering. Use a hand duster for easier, safer application.

Rinse with a Strong Stream of Water

A forceful spray of water from your garden hose will blast aphids off plants. With their tiny legs, they have trouble climbing back up the wet leaves and stems. Follow up with insecticidal soap to kill any stragglers.

Attract Predatory Insects

Ladybugs, lacewings, hoverflies, and parasitic wasps all feast on plant lice. Plant nectar-rich flowers to attract them. You can also purchase them from garden centers to release into your yard.

Use Sticky Traps

Yellow and blue sticky traps placed near plants capture winged adult aphids on the hunt for new colonization sites. This helps reduce airborne infestations.

Remove Ants

Ants have a symbiotic relationship with aphids, “milking” them for nutritious honeydew and protecting them from predators. Get rid of ants and beneficial insects will gain the upper hand.

Enlist Homemade Sprays

Two homemade remedies – tomato leaf spray and garlic oil – have proven effective against aphids. The process of how they work is most important:

Tomato Leaf Spray

Tomato leaves contain alkaloids that are toxic to aphids when ingested. To make a spray, boil 1 cup of fresh leaves in 2 cups of water for 20 minutes. Allow to cool, then strain and pour into a spray bottle. Spritz aphid colonies daily until they are gone. Reapply after rain.

Garlic Oil Spray

The sulfurous compounds in garlic have insecticidal effects on aphids. Steep several crushed cloves in 2 cups of vegetable oil for 24 hours. Strain and mix 1 cup of garlic oil with 1 pint of water and 1/2 teaspoon of mild soap. Transfer to a spray bottle and coat infested plants daily until aphids have vanished.

Preventing Aphids Naturally

Good garden sanitation and growing conditions go a long way towards preventing aphid infestations in the first place:

• Use row covers as a physical barrier when planting seedlings

• Rinse plants with water to remove eggs and larvae

• Avoid excess nitrogen fertilizer to discourage soft, juicy new growth

• Plant nectar-rich flowers to establish populations of beneficial insects

• Use reflective mulches like aluminum foil to confuse insects

• Tolerate minor damage and maintain small colonies to feed predator bugs

• Remove and destroy severely infested plants and prune out colonies

• Control ants that protects aphids from predators

With persistence using multiple organic control methods, you can win the battle against destructive aphid invasions. Pay close attention and intervene early before plant lice colonies get out of control in your garden and landscapes.