Family Aphidoidea, Greenfly, Blackfly
Almost any plant can be a host to aphids
- In the wild: Wild plants, shrubs, hedges, and trees
- In the garden: Ornamental trees and shrubs, including roses.
- On Crops: Most vegetables, fruits, and other plants
- Aphids range in size from ¼ in or less (1 to 7mm) and are soft-bodied insects that feed by sucking nutrient-rich liquids from foliage, stems, flowers, and roots. Aphids prefer succulent new growth. Aphids tend to congregate and, in numbers, can weaken plants significantly.
- Aphids can be white, black, brown, gray, yellow, light green or pink, and certain species have a woolly or waxy coating. They have pear-shaped bodies and long antennae; the nymphs look similar to the adults.
- Most species have two short tubes projecting from their rear. Adults are typically wingless, but most species can develop a winged form so that when food quantity or quality is lacking, they can travel to plants nearby, reproduce, and start a new colony.
- Aphids usually feed in large groups but are occasionally seen singly or in small numbers.
- While aphids generally feed on a wide variety of plants, certain species can be more attracted to certain plants. For instance, some species include bean aphids, cabbage aphids, and melon aphids.
The life cycle of aphids is complex and varies with each species. Eggs overwinter on woody stems, hatching in spring into “stem” females, which give birth to live nymphs continuously without having to mate. Nymphs mature in 1 to 2 weeks. In the fall, males and normal females are born and mate to produce overwintering eggs. In response to overcrowding or declining host plant quality, winged forms of aphids are produced to allow for mobility.
Damage and Detection
It is usually possible to detect aphid colonies with the naked eye, given their sheer numbers. Nymphs and adults suck plant sap, attacking leaves, stems, buds, flowers, fruit, and roots. There are many symptoms of aphid damage:
- Leaves can be misshapen, curled or stunted
- Flowers or fruit can be deformed
- Aphids can also secrete a sticky honeydew that promotes mold growth on leaves and fruit - the mold resembles black or brown powder on upper leaf surfaces.
- Ants may be found climbing plants with aphid colonies; they seek the honeydew and will remove aphid predators.
- Aphids can also spread diseases and viruses between plants
- Aphids also attract other insects, including ladybugs, that prey on them.
Prevention and Control
Aphids multiply quickly, so getting on them early is critical.
- For fruit or shade trees, spray horticultural oil in late winter/early spring to kill overwintering aphid eggs.
- Neem oil and insecticidal soaps are effective against aphids but need to be applied directly to the aphids to be effective.
- For vegetable crops and small ornamentals, spray frequently with water to dislodge aphids.
- Wiping or spraying leaves with a mild solution of water and dish soap can be effective if done several times weekly. A variation of this includes the addition of a pinch of cayenne pepper.
- Beneficial insects, such as ladybugs and wasps, feed on aphids. Attract these insects to your garden by providing a welcoming environment, including access to water and a range of flowering and other plants.
- Companion planting can deter aphids away from your plants. Aphids are repelled by catnip, garlic, chives, marigolds, dill, fennel, mint, and cilantro.
patrickkavanagh, Katja Schultz, Tamaki Sono, Andrew Cannizzaro, Flickr, nechaevkon, Shutterstock
While every effort has been made to describe these plants accurately, please keep in mind that height, bloom time, and color may differ in various climates. The description of these plants has been written based on numerous outside resources.