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Aphids

CROP IMPACTS: Trees and shrubs

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Family: Aphididae

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About Aphids

Aphids typically feed in a group setting and with their piercing and sucking mouth pieces they attach to tender plant tissue and draw out large amounts of plant sap. In the past they have been known to cause curled leaves, discoloration, galls, swollen branches or wilted leaves. However, they typically do not cause permanent damage to the trees and shrubs they eat. Some aphids can produce large amounts of a sticky substance called honeydew. When honeydew is dropped on cars, sidewalks and other objects it can be extremely frustrating to remove. Honeydew is also an attraction for wasps, flies, bees and ants, which are great indicators that you may have an aphid infestation.

Aphid Reproduction and Life Cycle

To summarize the life cycle of an aphid is difficult due to the fact that aphids have many variations and exceptions to their life. To start, stem mothers or wingless females reproduce throughout the summer months without the need for male fertilization. These particular stem mothers are unique in that they produce living young rather than eggs, which in warmer weather only take between 8 to 10 days to fully mature. Over time the plant where the stem mother and all of her offspring live becomes too crowded. At this point some offspring will start to develop into adults growing two, large, membranous wings. Once fully developed they will fly to new plants. By the end of summer, both males and females are produced. At this time it is about October and aphids will mate with the female laying black eggs with thick shells. It is in the egg stage where aphids can live through extreme temperatures and are able to live through winter. If you are located in a warmer climate, overwintering of the eggs may not occur. In March the eggs will hatch into wingless female nymphs and with several molts and continuous growth the young aphids become mature females. There is no male hatched in this process. Male aphids are winged and fly to a tree in October, and after, mating males will wait until those eggs have hatched and the aphid females have fully matured and will then mate with them.

Aphids Identification and Habitat

Identification

Aphids are small, pear-shaped, fragile insects. Their most distinguished feature is a pair of soft, tube-like projections near the back of the stomach. They can come in many colours including black, green, red, yellow or colorless, with some species of aphids being covered in long, waxing, white threads. Depending on the variety of aphids they can be winged or wingless, measuring from 1 to 3mm long. If Aphids are winged, they are transparent wings with some veins running through them. They also have thin legs, long antennae and come equipped with mouthparts that have the capability to pierce and suck plants.

Aphid Varieties

  • - Pea Aphid (Acyrthosiphon pisum Harris)
  • - Green Peach Aphid (Myzus persicae)
  • - Corn Leaf Aphids (Rhopalosiphum maidis)
  • - English Grain Aphids (Sitobion avenae)
  • - Corn Root Aphids (Rhopalosiphum maidis)
  • - Blue Alfalfa Aphids (Acyrthosiphon kondoi)
  • - Cowpea Aphid (Aphis craccivora)
  • - Pink pea Aphid (Acyrthosiphon pisum)
  • - Spotted alfalfa Aphid (Therioaphis maculata)

Aphid Habitat

Aphids can be found throughout North America eating any part of trees, shrubs, vegetables and flowers including their buds, flowers, fruit, roots, foliage and twigs.

Aphids Prevention and Control Methods

With the high rate of reproduction of aphids and the potential damage these pest can cause makes it important for early detection and timely management. Using several approaches to eradicate aphids is often necessary for optimum control.

Prevention

Prevention against aphids can be done by the removal of weeds. Aphids can live on many types of weed species that may or may not be reached by pesticides. Weeds that are not dealt with create an environment for aphids to establish and then rapidly spread.

Cultural and Chemical Control

Aphids are quite defenseless pests and can often be controlled by natural enemies like aphidlions, birds, ladybird beetles and lacewings. Natural elements can also reduce the population of aphids by cold temperatures and heavy rain. If aphid infestations are detected early and before adult aphids have winged, control can be reached by spot treatments, or by removing infested plants. Once large infestations of aphids have been detected, they can be managed by horticultural oils and insecticidal soaps. If population of aphids have gotten out of control, use registered insecticides that contain either diazinon, dimethoate, malathion, or permethrin. Make sure that before application of any insecticide to scout for predators and double check that the insecticide is not toxic to the plants it will come in contact with.

Latin / Alternative Aphids names

  • - Plant lice
  • - Plant Louse
  • - Greenfly
  • - Blackfly
  • - Ant cow

Sources

http://www.agr.gc.ca/eng/science-and-innovation/agricultural-practices/agroforestry/diseases-and-pests/aphids/?id=1200069266247

http://www.omafra.gov.on.ca/english/crops/facts/06-081.htm

http://www.biology-resources.com/aphid-01.html