These microarthropods are the bane of many greenhouses and gardeners. There are many species of Aphids and come in a variety of colors and forms. A significant infestation will damage plants and make them undesirable for human consumption.
Aphids use a needle like appendage called a proboscis to suck sap from plants. This action alone can introduce pathogens to the plant depending on your circumstances. Theylater excrete whats known as "honey dew" leaving a shiny dew on the surface of the plant. That honeydew is a food source for some pathogenic fungi which can later coat the plant.
Cause: Aphids are typically attracted to plants whose sap is low in sugar or phyto-chemicals, this is determined by the health of the soil the plant inhabits. The presence of a complete soil food web determines the ability of a plant to source the micronutrients it needs to ward off the attacks of insect pests.
Aphids also appear towards the end of the growing season when there is lower amounts of light which limits the plant's ability to photosynthesize which leads to the slow deterioration of the overall health of the plant.
Solutions: Improve your soil's health. Reintroduce the soil food web to your soil. That means limiting tillage and getting away From chemical inputs. This takes time and patience. Proper methods of thermophilic composting, mulching, crop rotation, and if you're brave, cover cropping can help your soils provide a habitat for all the organisms in the Soil Food Web.
In the meantime, there are aphid predators that are quite effective at stopping an infestation. Ladybug (Hippodamia convergens) larvae are a favorite due to their charismatic nature. But our our greatest success has come from parasitic wasps (Aphidius colemani) which lay their eggs inside the body of aphids and multiply at the same rate if not faster than aphids. The key is to not use pesticides and then these wonderful organisms should remain in your environment to constantly check aphid populations. Aphid life cycle.
Aphids will clone themselves and lay eggs. Individuals from eggs will hatch wings and spread throughout an area. They aren't the. best flyers, but if gone unchecked, especially in a greenhouse, Millions of aphids will appear. You can use mineral oil or other natural pesticides but these "often indiscriminate and kill beneficial insect predators. A complete above ground and underground ecosystem will naturally check many insect pests.