Aphids are an insect pest that most gardeners have experienced at one time or another. Knowing more about these hungry insects will help you identify aphids, spot their telltale damage on plants and utilize the most effective organic control methods that can prevent a small aphid problem from turning into a massive infestation.
Like many insect pests we discuss here, aphids are not a single species but a group of related species grouped in the family Aphididae. Worldwide there are thousands of aphid species with a range of different habitats from the well-known aphid species that feed on leaves and flowers to subterranean aphids that prey on root systems like the corn root aphid. Within North America, there are six wide spread aphid species that are common pests in many vegetable gardens including:
- green peach aphid (Myzus persicae)
- potato aphid (Macrosiphum euphorbiae)
- melon aphid (Aphis gossypii)
- turnip aphid (Lipaphis erysimi)
- cabbage aphid (Brevicoryne brassicae)
- bean aphid (Aphis fabae)
As their common names suggest, these six species attack a wide range of crops during the growing season. In fact you would be hard-pressed to find an edible plant that is not impacted by an aphid species.
Aphids are small soft-bodied insects sometime known colloquially as “plant lice.” Because of their small size, aphids can be difficult to identify to the species level by non-entomologists. In general, most pest aphid species range in size from 1/16 inch to 1/8 inch long. Adult aphids have six legs attached to pear-shaped bodies that may or may not feature wings. Body coloration varies both between species and within species with green, grey, red, yellow and dark-colored aphids being quite common. The rear of the aphid’s body has two distinctive pipe-like structures, known as cornicles, that are used to emit a defensive pheromone secretion that warns neighboring aphids of an impending predator threat. Aphids have piercing and sucking mouthparts that utilize needle-like structures to puncture leaves and suck up plant sap, which is their primary food and sadly the source of many headaches for gardeners.
Perhaps one of the most notable and fearsome aspects of aphid family is their prolific reproductive ability. Female aphids are able to reproduce asexually bearing live young aphid clones or reproduce sexually laying fertilized eggs. From hatch or live birth most aphid species can reach sexual maturity between six and 12 days, allowing for an incredible 10 to 20 aphid generations in a single season. The dual reproductive strategies of the aphid family combined with a fast maturity rate allow aphid populations to grow exponentially if not managed by natural predators or cultural intervention by gardeners.