All About Aphids, and How to Kill Them

Good things come in small packages, or so the idiom goes. But annoying, destructive things can also come in small packages: just think about the crop-destroying aphid, sometimes referred to as “plant lice.” There is no lack of credible material on the internet to help you understand and control aphids. However, we’ve done the hard work for you and scoured dozens of sites to compile the most helpful information about this common garden pest, including how to control the population. Rely on this comprehensive article to learn about aphids, how to tell if they are present in your garden, what crops they most frequently damage, and how to be free of these tiny terrors.

Aphids at a Glance

Aphids are soft-bodied pear-shaped insects that come in a variety of colors like black, brown, red, pink, or green, and may even have transparent wings. On their exterior, they sport two short tubes that protrude back from their abdomen and have long antennae.

Aphids start out with wings held close to the body. If you see only winged aphids, this is a perfect time to engage in an all-out offense on the colony. Once they lose their wings, they are here to stay. What is worse than seeing these wingless visitors? Seeing a mixed aphid colony in which some have wings and some don’t: this means the area is overpopulated and the new winged aphids are determined to find a new home in a nearby crop.

Shockingly, there are over 4000 species of aphids, which means they can appear in almost any environment, in any condition. Aphids feast on most fruit and vegetable plants, flowers, ornamentals, and shade trees.

How can I tell if I have aphids?

Perhaps you haven’t seen them (they are only 1/16 to 1/8 of an inch long), but more than likely you have seen evidence of their damage. Because aphids suck plant sap, one way to identify an infestation is to look at your leaves, branch tips, and flowers. They may appear distorted, deformed, curvy, or may just completely drop off. Further, aphids’ excrement is in the form of a sweet, sticky honeydew. This honeydew will develop a sooty mold fungus which blocks sunlight from getting to that area of plant leaf. It also attracts ants.

Aphids can transmit viruses from plant to plant. Look for yellow or mottled leaves plus stunted plant growth. Squash, cucumber, pumpkin, beet, melon, chard, bean, bok choy, lettuce, and potato are most commonly affected by aphid viruses. Keep an eye out in early spring for this type of damage, which is when aphids leave their winter habitats.

Why are aphids so hard to control?

Aphids’ reproductive systems work in overdrive mode. Females are asexual, meaning they can produce multiple young per day without even mating. Add to this her ability to reproduce with the males born in late summer and you end up with a steady stream of destructive aphids. It only takes 10-14 days for an infant aphid to become a fully grown adult.

Ways to control aphids

Here are 20 pesticides—15 natural and 5 synthetic—that can be used to control aphid populations.

Natural Remedies

1. Martha Stewart advocates the use of this do it yourself, all natural combination: peeled onions and garlic cloves combined with cayenne pepper and water. The beauty of this formula is that it will remain potent for up to one week if refrigerated.

2. AzaMax comes in a small 4-ounce bottle. Its active ingredient, Azadirachtin, is present in popular neem seeds. Customers agree that it works, and while the bottle costs $20, you only need to use 1 tablespoon per gallon of water.

3. Add 1 ounce of apple cider vinegar to 3 ounces of water. This formula will also work on fleas, but remember that some plants cannot tolerate cider’s acidity.

4. Garden Safe Insecticidal organic soap is derived from plant fatty acids and kills insects upon contact. It won’t harm honeybees or ladybugs, either. It’s also affordable and effective: 101 customers give this $5 product a 4-star average.

5. Or, use a bar of $4.50 Fels Naptha Soap. Grate the soap into water and you have your own economical insect soap. Learn how to make it here: http://www.littlehomesteaders.com/2013/09/homemade-insecticidal-soap/

6. A combination of garlic, onions, limes and another secret weapon–chilies—may do the trick. Stick a citrus fruit, chilies, peeled onions and garlic cloves into a blender with water to produce this mixture.

7. Believe it or not, a simple and affordable mixture of water and dish soap can wash away those pesky pests. Just combine ½ teaspoon of dish soap with 1 quart of water in a spray bottle.

8. Espoma Earth-tone 3n1 kills fungus, insects, and mites. The 16-ounce bottle of concentrate uses organic pyrethrins and sulfur and must be reapplied every 7-10 days or after rainfall. It is one of the more expensive organic solutions at nearly $20 since it uses 5 ounces of solution per gallon of water.

9. Here’s a mixture-free option. Since aphids are attracted to the color yellow, place something yellow in your garden (a tennis ball or yellow plastic cup will do) and cover it with petroleum jelly. The aphids will flock to the yellow-colored object and get stuck. Easy maintenance involves nothing more than periodically throwing away and replacing the object.

10. If you don’t feel like doing this yourself and are willing to shell out some money, these $13 yellow sticky aphid papers will serve the same purpose (15 per package).

11. Keep it simple and use lemon juice. Remove and boil lemon rinds for about 30 minutes and juice the lemon itself into a spray bottle. Squirt the lemon juice on the aphids and then squirt the boiled rind water in the soil to discourage re-habitation.

12. Captain Jack’s DeadBug Brew contains spinosad, a bacteria that lives in soil. Spinsosad was discovered in 1982 on a Caribbean island, thus the product’s fun name. A 16-ounce bottle of concentrate costs $17 and only requires 4 tablespoons per gallon of water. One consumer warned that it kills bees (as indicated directly on the product’s usage label), so if you have nearby honeybees, consider another product.

13. Mycoinsecticide is another biological agent that can stop aphids via transmission of a fungal infection. BotaniGard uses this insecticide type with no added chemicals, meaning it’s safe to use around your crops. $77 will buy you 1-pound of wettable powder to make your own solutions; this should last you awhile.

14. Any aphid control suggestion would be incomplete without mentioning the advantages of beneficial insects. When possible, attract aphid predators to your gardens, especially ladybugs. Ladybugs love cilantro, dill, fennel, caraway, wild carrot, and yarrow. Or, buy your own ladybugs. You’ll get 1500 for $7.50 and each bug may eat up to 50 aphids per day. Release them at sundown for best results, as ladybugs don’t fly at night.

15. Mineral oil is another potential aphid killer. Also known as horticultural oil, Monteray sells a 80% mineral oil solution for $25. Two to five tablespoons get mixed with a gallon of water from this 5-quart bottle, which also may contain petroleum distillates. Note that this product is toxic to fish and also harmful if absorbed through the skin.

Synthetic Products

16. Ortho Flower, Fruit, and Vegetable Insect Killer can be used in your vegetable garden. The main ingredient is acetamirprid, an odorless pesticide developed by Aventis CropSciences. While it is classified as unlikely to be a human carcinogen, it may be mildly toxic to bees. At $11.50 per 32-ounce bottle, it received favorable reviews.

17. An even more well-reviewed solution is Permethrin SFR. The same size bottle will cost you twice as much as Ortho’s product, but the concentrate will yield 20-96 gallons, according to the manufacturer. Despite the cost, almost 200 customers have given this product a 4.5 star average. The active ingredient is Permethrin itself, which also has medicinal applications for scabies and tick bites.

18. This Spectracide concentrate can make up to 96 gallons for only $14 with consistent positive results. Malathion, its active ingredient, is classified as having low human toxicity and is also used for similar medicinal applications as Permethrin.

19. FenvaStar uses 3.5% Esfenvalerate to control aphids; Esfenvalerate is a synthetic version of pyrethroid insecticide. In the U.S., a small amount is permissible in food and food manufacturers, so this product is deemed safe for vegetable gardens. Mixing 1 ounce of concentrate per gallon of water means you will pay about $2.50 per mixture.

20. If aphids have infested your vegetable transplants, products containing Spirotetrama may help. KONTOS solution can be used as a spray or drench and contains two pounds of Spirotetrama per gallon. This option is the most invasive, being distributed throughout the plant roots and new shoots, as opposed to simply coating the surface of leaves, like other products. This is also the most expensive option at $160 dollars.

Creative Commons Flickr photos courtesy of Michael M. S. and Umberto Salvagnin