Their success is due in part to the asexual reproductive capabilities of some species. About 4,400 species are known, all included in the family Aphididae. Around 250 species are serious pests for agriculture and forestry as well as an annoyance for gardeners. They vary in length from 1 to 10 millimetres. Natural enemies include predatory ladybirds, hoverfly larvae, parasitic wasps, aphid midge larvae, crab spiders, lacewings, and entomopathogenic fungi such as Lecanicillium lecanii and the Entomophthorales.
There are various insecticides that can be used to control aphids, including synthetic insecticides and plant extracts/products that are thought to be more eco-friendly. For example, neem and lantana products can be used to protect plants against aphids. For small backyard infestations, simply spraying the plants thoroughly with a strong water jet every few days may be sufficient protection for roses and other plants. An insecticidal soap solution can be an effective household remedy to control aphids and other soft-bodied arthropods. It will only kill aphids on contact and has no residual action against aphids that arrive after application. Soap spray may damage plants, especially at higher concentrations or at temperatures above 32 °C. Some plant species are known to be sensitive to soap sprays.
Integrated pest management of various species of aphids can be achieved using biological insecticides based on fungi such as Lecanicillium lecanii, Beauveria bassiana or Paecilomyces fumosoroseus. Aphids may also be controlled by the release of natural enemies, in particular lady beetles and parasitic wasps. However, since adult lady beetles tend to fly away within 48 hours after release, without laying eggs, it requires repeated application of large numbers of lady beetles to be effective. For example, one large, heavily infested rose bush may take two applications of 1500 beetles each. In reality the only cost effective situation in which mass release of natural enemies makes sense is in closed or semi closed environments such as glasshouses or polytunnels.
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