There are approximately 5,000 species of aphids in the family Aphidoidea, all of which feed on plant sap. They tend to live in colonies with hundreds or thousands of individuals. When populations become too large, or food sources run low, aphids can produce offspring with wings that disperse to new plants for feeding.
Aphids can feed on every part of a plant, including the roots. In this article, we will cover everything you need to know about aphids from what they look like to how to get rid of them so you can keep them from damaging plants around your home. We will also cover the most common species, their lifecycle, and the damage aphids cause so you can get rid of them quickly.
What Are Aphids?
Aphids are members of the insect order Hemiptera. They have piercing, sucking mouthparts which they use to feed on sap from plants. Some species can cause significant damage to certain plants. Aphids cause millions of dollars in damage to crops each year.
What Do Aphids Look Like?
Aphids are pear-shaped insects with soft bodies. They are 2 to 4mm in length and can be a variety of colors[1]. They may or may not have wings. Individuals with wings hold them in a tent-like position over their backs.
They have two projections at the end of their abdomen called chronicles. These make them easily recognizable from other small insects.
Types Of Aphids
There are thousands of aphid species, but some are much more common than others. The table below covers the most common species found in your garden or on ornamental plants.
| Name | Coloration | Host Plants |
| Green peach aphid (Myzus persicae) | Wingless individuals are a pale yellow-green or pink; winged individuals have a black head | Many vegetables, flowers, fruits, and woody ornamentals |
| Cabbage aphid (Brevicoryne brassicae) | Gray-green color that can look gray to white due to the waxy secretion that covers their body | Cole crops and other plants in the mustard family |
| Melon (cotton) aphid (Aphis gossypii) | Variable in color from yellow to green to black | Cucurbits, citrus, carrot, flowers, and woody ornamentals |
| Bean aphid (Aphis fabae) | Dark green, brown, or black | Legumes, woody ornamentals, and flowers |
| Potato aphid (Macrosiphum euphorbiae) | Pale to bright green with a large brownish spot on the top of their abdomen | Potato, tomato, spinach, lettuce, and many others |
| Crapemyrtle aphid (Sarucallis kahawaluokalani) | Pale yellow-green with black spots on their abdomen | Crape myrtle |
| Rose aphid (Macrosiphum rosae) | Green, pink, or purplish | Roses |
Aphid Life Cycle
Aphids have complex life cycles with many variations. They go through incomplete metamorphosis. This means that immature aphids look very similar to adults and don’t go through a pupal stage. Instead, they molt several times, shedding their skin as they grow until they reach sexual maturity.
Females can give live birth to offspring with or without wings. They often produce wingless female offspring until populations get too high or food sources are depleted[1]. They produce males near the end of the plant growing season in the fall. They can then mate with males and produce eggs that can survive the winter.
Aphids produce as many as 12 offspring per day. New offspring mature into adults and start reproducing themselves in as little as 7 days. That means a single aphid can turn into more than 7,000 aphids in as little as 2 weeks.
Signs Of Aphids
Honeydew is the most common, noticeable sign of aphids but it generally goes unnoticed until populations are large. Aphids excrete honeydew which is a sugary byproduct of their feeding. Black sooty mold will grow on honeydew and cause surfaces covered in honeydew to turn black[1].
Aphid Damage
In small numbers, most aphids don’t do much damage. When populations increase, some leaves may begin to yellow and new shoots can become distorted[1]. Some species release a toxin when they feed which can lead to tissue distortion even when populations are small. A few species of aphids will cause galls on leaves[1].
The most detrimental damage caused by aphids is through disease transmission. A single aphid only has to feed on a plant for a few minutes to transmit certain diseases[1]. Disease transmission often leads to significant damage or death to plants by aphids.
How To Prevent Aphids
You can prevent aphids from feeding on young plants most susceptible to permanent damage by growing them under row covers. Row covers consist of netting and support poles, keeping insects from getting to plants.
Removing weeds can also help to prevent aphids. Many aphids can feed on weeds as well as your ornamental landscape plants and vegetable gardens. By removing weeds you can reduce the risk of aphids utilizing weeds and then moving into your garden.
Another way to prevent aphids is to use slow-release fertilizers and don’t use large amounts all at once. Aphids often prefer to feed on new growth which is promoted by fertilizers. By using a slow-release fertilizer and spreading out fertilizer applications over time, you prevent plants from having an abundance of new growth all at once. A flush of new growth can attract aphids and allow populations to increase.
How To Get Rid Of Aphids
First, make sure you keep an eye out for aphids and their damage. The sooner you detect aphids and start the process of getting rid of them, the easier it is. Once aphid populations get too large, plant leaves start to become distorted and twisted providing hiding spots for aphids to escape other aphid treatments.
Many natural enemies will feed on aphids and help get rid of them. Parasitoid wasps, ladybugs, green lacewing larvae, and several other insects eat aphids[1]. Limit the use of broad-spectrum, residual pesticide use to avoid killing aphids’ natural predators.
Another natural way to manage aphids is by knocking them off with a blast of water from a hose. Once wingless aphids are removed from plants, they typically can’t make it back to them[1]. This will also help wash off their honeydew and prevent sooty mold growth.
If insecticides are needed, when populations become too large, it is best to stick to using insecticidal soaps and oils. These products will coat and suffocate aphids on contact. They also reduce the chances of killing natural enemies of aphids.
Frequently Asked Questions
There are several ways for aphids to infest indoor plants. Some plants may already be infested when you bring them into your home since they can be difficult to detect until populations are large. Winged aphids can enter the home through open doors and windows. You or your pets may also bring these tiny critters into the home unknowingly.
Root aphids can be a serious pest of indoor plants since they live in the soil feeding on roots. However, even root aphids cannot live for long in potting soil. They rely on plant tissue sap to survive and will die within a few days in the absence of the plant hosts to feed on.
Most plants can easily recover from the damage aphids cause to their tissue. However, the bigger concern about aphids is their ability to transmit plant disease. If an aphid introduces a disease to your plants, depending on which disease it is, they may not recover.
Due to aphids having wings, it is nearly impossible to keep them from coming back. The only way to ensure they don’t harm plants in your garden is to grow plants under row covers. For many plants, this isn’t possible. Fortunately, most plants recover from the feeding damage caused by aphids.
Aphids can cause aesthetic damage to plants but typically don’t harm them. However, they are harmful if they transmit plant diseases when they feed. Luckily, unlike mosquitos and ticks, aphids do not cause any type of harm to humans or pets.
References:
[1]Flint, M. L. (2013). How to manage pests: Aphids. UC IPM Online. Retrieved October 21, 2022, from http://ipm.ucanr.edu/PMG/PESTNOTES/pn7404.html