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Aphids, Plant Lice, Pest Insect, Plant Louse,
Aphididae, Honeydew, Greenflies, Greenfly

Aphids, or plant lice, also known as greenflies, are a very successful group of insects, one of our biggest competitors for plant food. They have a high reproductive rate and can scatter pretty easily, using the wind to help them along. Winged aphids can be blown across the ocean, up to 1,000 miles, and survive! Aphids of the Midwestern U.S. are typically yellow, green, black or even reddish in color. They appear in the fossil record as early as the Cretaceous period, so they have been around for a while.

Aphids use chemicals called pheromones for communication and defense. If bothered, aphids eject an alarm pheromone. Neighboring aphids take this as a hint to vacate the premises a.s.a.p., and promptly drop to the ground. Once they feel safe and sound, the aphids look for vertical lines to find their host plants, and proceed to climb back aboard.

aphids, plant lice, aphididae, greenflies, closeup
aphids, plant lice, aphididae, greenflies, closeup



aphid, apterae, wingless, aptera
aphid, apterae, wingless, aptera

aphid, alatae, winged, alata
aphid, alatae, winged, alata

Several aspects of aphid development are determined by their host plants and the season. Some aphids, called apterae, are born without wings and related muscles, gaining enhanced reproductive abilities instead. Without the physical resources dedicated to power flight they can produce more offspring per female. Winged aphids are called alatae. Some female aphids, viviparae, have live young without the aid of a male, while others reproduce sexually.

green aphid, winged, closeup, greenfly
green aphid, winged, closeup, greenfly

wingless, aphid, closeup
wingless, aphid, closeup


Aphids feed on the sap of various plants, with some species preferring specific types of plants. Plants of the rose family are popular with some, while bamboo, willow, oak, walnut, maple, sugarcane, lettuce, alfalfa, and more, are popular with others. One serious pest, Grape Phylloxera, is a relative of the aphid. It prefers to dine on grape vines. For the most part, aphids have evolved with the plants they like to eat, but sometimes they switch to different ones.

Aphids secrete a sticky liquid called honeydew when they eat. If you've bumped into a sticky plant with aphids on it, or have been rained on by tiny sticky drips, you've been honeydewed! Adult aphids are sap suckers, drinking it from most parts of most plants, including flowers, fruit, leaves, stems and even roots.

yellow, aphids, plant lice, aphididae
yellow, aphids, plant lice, aphididae

Some ants tend aphids for their honeydew treasure. When stroked by ant antennae, aphids raise their bottoms, offering up a drop of honeydew. Ants will go as far as moving aphids to greener pastures when a food source is exhausted, or protecting them from the elements, like a heavy rain. The relationship between ants and aphids is mutually beneficial. Ants get food and aphids get protection. Ants drive off aphid predators like lacewings and wasps.

ants tending aphids, collecting honeydew, mutually beneficial
ants tending aphids, collecting honeydew, mutually beneficial

ants tending aphids, collecting honeydew, mutualism
ants tending aphids, collecting honeydew, mutualism

ant eating aphid honeydew, farming
ant eating aphid honeydew, farming

Aphids have specialized feeding parts they use to get sap from their favorite food sources. Their saliva loosens plant cell bonds, allowing aphid mouth-parts easy access to plant tissue. Aphid digestive tracts have special cells that contain bacteria which aid in the synthesis of nutrients from plant sap. Aphid moms pass the bacteria on to their offspring.





winged and wingless aphids
winged and wingless aphids

green aphids, wingless, group, shed skin
green aphids, wingless, group, shed skin

Aphids are one of the top agricultural pests. They're especially bad because they damage plants in several ways. Aphids often slurp enough sap from their food sources, that the plants starve. Their discharge builds up and damaging mold grows on it. Aphids can even transmit viruses from plant to plant. Virus-infected plants turn yellow, attracting even more aphids!

seven spot ladybug hunting aphids, eating
seven spot ladybug hunting aphids, eating

green aphids closeup picture
green aphids closeup picture
Aphids can be controlled fairly effectively with natural enemies. Wasps, lacewings, ladybug beetles and aphid midges all do serious damage to aphids. There are some forms of fungi that kill aphids as well. Chemical poisons should not be used against aphids because they develop resistance to them, and they aren't good for people either. Something as safe and simple as garlic water will repel aphids. They are kind of plant vampires, so that makes sense! So grab your garlic spray and watch out for falling honeydew!

Andrew Williams / CritterZone.com
Literature cited
Carde, Ring T. 2003 Encyclopedia of Insects Academic Press pgs.32-37
The aphid, plant lice, pest insect, honeydew, mutually beneficial ant and predator ladybug pictures on this page are available for commercial stock photography license. All text and photos that appear on this webpage are copyrighted and may not be copied or used in any way without permission from CritterZone.

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black aphids on stem
black aphids on stem