Aphids are probably the most common garden pest in the whole world. There are over 4.000 different species of aphids spread out across every continent except Antarctica. Here in Colorado, according to the CSU Extension Office, “few plants grown (here) do not support at least one aphid.”
Symptoms and Signs
Aphids can be extremely varied in appearance (coming in green, white, black, brown, gray, yellow, or even pink) but all are small, less than ¼ of inch long. Aphids feed by sucking juices from plant leaves, stems, buds and roots. This can cause leaves to curl, yellow or wilt. New leaves can become stunted, too.
Another tell-tale sign of aphids is a sweet, sticky substance called honeydew. This is secreted as waste by aphids during feeding. Honeydew can be its own problem as it can attract sooty mold, ants and other pests. Some aphid species can also cause galls to form on the leaves or stems of plants.
The good news is that although aphids can cause lots of unsightly damage, they rarely can kill a well-established tree or shrub on their own. However, it’s still important to keep them in check because aphids reproduce fast and a weakened plant is susceptible to many other, deadlier pests and disease.
When trying to control a garden pest, it always helps to understand their lifecycles. And aphids have a particularly strange one. In the spring, female aphids hatch from overwintered eggs. These females are called “Stem Mothers.” Stem mothers go onto reproduce asexually, making little clones of themselves through a process called parthenogenesis. Stem mothers reproduce prodigiously throughout the summer. In the fall, with winter coming on, stem mothers begin to produce both male and female aphids. The males and females mate, producing eggs that will overwinter, to hatch again next spring.
Aphids are soft bodied insects with few natural defenses, so there are many, many different control options available. Below we've listed some of the most common aphid control methods, each with their own pros and cons. We recommend starting with number one, then if that doesn't take care of the problem, move up through the list to stronger and stronger controls.
Believe it or not, one of the best control options for aphids is good old-fashioned H2O. Washing off the affected plant with a good, strong blast from the hose is often enough to kill small outbreaks of aphids, especially when caught early. Even if they survive the blast, very few have the strength to return to the plant from the ground.
Pros: Super easy and cost-effective. If you think you notice signs of aphids, grabbing the hose is always a good first step.
Cons: While a hose blast is great for small or early outbreaks, it might not be enough to contain bigger problems.
2. Natural Predators
Aphids are soft, tasty little snacks for a variety of animals. The most popular aphid-eaters are the gardener’s old pals, ladybugs. And they do like to eat! One ladybug can eat up to 5,000 aphids in its lifetime! As they munch, ladybugs start to lay their own eggs, giving you a population of hungry aphid diners for extended control.
Pros: Using lady bugs is a great natural solution to aphids. It’s easy (no spraying or mixing) and even kinda fun!
Cons: Ladybugs are prodigious feeders, but this me