Aphids are a common insect pest found in both flower and vegetable gardens. Nearly every yard or garden has aphids, which typically isn’t a problem. However, a severe aphid infestation can wreak havoc on your vegetables and flowers. Knowing how to identify and control them is essential to your gardening success. Aphids damage plants, but are aphids harmful to humans?
What are aphids?
Aphids are tiny pear-shaped insects measuring between 1/16 and 1/8 inches long. Some aphids are wingless, while others have wings. They may be black, brown, red, yellow, or green. Aphids have two cornicles (sometimes called tailpipes) on the end of the abdomen.
Aphids are sucking insects that feed on plants. They suck the sap from tender new growth such as buds, new leaves, and developing stems. Aphids typically can be found on the undersides of leaves and along the plant’s stems.
Where do aphids come from?
Aphids overwinter as eggs. The eggs hatch in the spring, producing the first generation of aphids. According to CANNA, the first cycle of aphids to hatch in the spring are all females. These aphids live for nearly 30 days and can each produce 80 offspring.
During the spring and summer, the aphids reproduce asexually, the new aphids are born alive, and all the offspring are females. However, as fall approaches, a cycle of aphids develops into both male and female aphids. The males then breed with the females, and the female lays eggs that will overwinter on host plants.
In the summer or early fall, when the food supply decreases or the area is overpopulated with aphids, winged females develop and fly away to new areas and begin producing wingless females, says the University of Wisconsin-Madison. It is common to see flying aphids in the fall as they expand their territory.
Are there different types of aphids?
There are approximately 1,350 species of aphids in North America. Most are similar in appearance other than their color. Some of the most common aphids include:
- Green Peach Aphid (Myzus persicae): This yellowish-green or reddish aphid feeds on over 500 host plants and is the most common aphid in home gardens and flowerbeds.
- Cabbage Aphid (Brevicoryne brassicae): This aphid is a grey-green with a waxy covering. It attacks members of the brassica family, such as cabbage, cauliflower, broccoli, Brussels sprouts, kale, and kohlrabi.
- Potato Aphid (Macrosiphum euphorbiae): These aphids are pink or green and hatch out on rose bushes in the spring, feeding on new growth. Later in the season, they migrate to potato and tomato plants, where they can introduce viruses and mosaic diseases. They also attack ornamental plants and weeds.
- Melon or Cotton Aphid (Aphis gossypii): These dark green aphids feed on melons but can be found on nearly all vegetable plants.
- Rose Aphid (Macrosiphum rosae): Rose aphids are pink or light green and infest roses.
- Woolly Apple Aphid (Eriosoma lanigerum): These aphids are unique as they produce waxy thread-like filaments on the abdomen, giving them a fuzzy appearance. They feed on apple trees.
Are aphids harmful to humans?
Aphids are sucking insects that feed on plant parts. They do not bite humans or animals. Aphids do not pose a threat to humans.
Can aphids live in your hair?
Aphids feed on plant material and do not feed on humans or animals. Aphids do not live in human hair. If an aphid accidentally contacts your hair or pet’s fur, it will not stay there. It will seek out plants.
Are aphids harmful to plants?
Typically, aphids do not do a lot of damage to plants in the garden, but a severe infestation can lead to many issues.
- Weak Growth: Aphids suck the sap from plants, leading to weak growth. Leaves may turn yellow, become misshapen, curl or become stunted. Fruits may appear deformed or distorted, and galls may form on roots, stems, or leaves.
- Fungi: Aphids excrete a thick, sticky fluid often referred to as ‘honeydew.’ This can encourage the growth of sooty mold, a fungal growth that grows on plant material. Leaves or stems appear black when sooty mold sets in. Sooty mold does not harm the plant but does ruin its appearance.
- Disease: Aphids can spread diseases, like viruses and mosaic diseases that threaten your plants. Mosaic disease causes weakened or stunted growth and deformities in the foliage or fruits of the plants. There is no cure for mosaic disease.
How do you get rid of aphids?
- Spray with water. You can generally dislodge aphids from your plants with a strong stream of water from your garden hose. Unless the aphids have entered the winged stage when they fly to locate a new host, they will not likely find their way back to your plants.
- Use insecticidal soaps. This includes neem oil or horticultural oils. The soap or oil must contact the aphid’s body to be effective.
- Use a mixture of dish soap, vegetable oil, and water. Add a teaspoon of oil and ½ teaspoon of dish soap to a quart of water and shake to blend it. Fill a spray bottle with the mixture and use it to spray the aphids. The solution coats the aphid’s body and blocks its breathing pores, killing the aphids.
- Use diatomaceous earth. This natural insecticide is nontoxic and dehydrates the aphids on contact. Use care not to use diatomaceous earth when your plants are in bloom, as it will also kill pollinators like bees and butterflies.
What are the natural predators of aphids?
Several insects attack or feed on aphids. Introducing them to your yard or garden will help keep aphids under control. Try purchasing and releasing these natural predators to control the aphids in your garden.
- Lacewings: Green and brown lacewings help control aphids as the larvae feed on aphids. They can be purchased and released in the garden.
- Lady Beetles: The famous ladybug has a ferocious appetite for aphids. They eat both larvae and adult aphids. Lady beetles are readily available for purchase and release in the garden.
Seeing a few aphids in your garden is no reason to panic. These tiny insects can be found in nearly every garden or flowerbed. However, a severe infestation can cause plant damage and pose a risk to your garden. Learning how to identify and control them will keep aphids at bay.