Aphids

Aphididae

Aphids, Aphid, Plant Aphid, Greenfly, Blackfly, Green Fly

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One of the most common garden pests, Aphids are small sap-sucking insects in the Superfamily Aphidoidea. There are over 4000 species worldwide, and in low to moderate numbers, they're not too harmful to garden plants. They're often seen feeding in clusters on new plant growth. However, a general decline in plant vigour will be noticed with a substantial infestation. Aphids feed on the cell contents of plant leaves, which over time reduces the green leaf area available for photosynthesis.
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Traits

Aphids produce large amounts of honeydew, which may attract ants or black sooty mould.
Aphids are predated by many other insects and garden animals.

Appearance

Adults: Aphids may be green, brown, yellow, black or red depending on species and their food source. They are rather small and have soft, pear-shaped bodies. Some may have a waxy or woolly coating and are known collectively as as 'Woolly aphids'. Aphids possess complex life cycles, spending prolonged periods on different plant species depending on the time of year. During these times, a female can produce winged, or wingless offspring. For this reason, some aphids will lack wings. Nymphs: Very similar to adults but the wings will be absent, and sometimes they will appear paler in colour. Eggs: The eggs look like tiny white dots, generally associated with the main colony beneath the leaves of the host plant.

Symptoms

Colonies of aphids clustered on young stems, leaves and buds. Yellow leaves. Leaf and stem distortion. A sticky substance on the plant or leaves, known as honeydew. Honeydew can attract ant colonies, and black sooty mould. Premature leaf fall. Plants generally looking 'unhappy'.

Activity

Diurnal

Personality

Order

Hemiptera

Family

Aphididae

Metamorphosis

Incomplete

Distribution

Worldwide

Biological treatment

General good housekeeping can help prevent any insect pest infestation. Before planting, be mindful of the space you leave between crops and shrubs. Weeds and plant debris can facilitate a bad pest infestation. Planting strong-smelling herbs such as basil, chive, Allium and mint are believed to deter aphid activity. Aphids aggregate in areas of new growth, so be sure to check in all the nooks of plants, including beneath the leaves. Aphids can also be treated with a strong jet of water to dislodge them from the plant; or, a light, soapy mixture applied to the plant or even just squashing them. A mixture of tomato leaf and distilled water is believed to deter aphids. Once the leaves are drained, dilute the remaining mix with 1-2 cups of water. Tomato plants contain the same allergens as nightshade. It's not advised to use this method if allergic to nightshade. Alternatively, garlic or chilli-based spray diluted with water is thought to act as a natural insect repellent. Aphids can sometimes attract ants to the infested area because of the honeydew they produce. An ant colony will protect aphids so they can farm their honeydew. Placing ant traps near infested plants will help to prevent any secondary infestations. Aphids possess an array of natural enemies (ladybirds, wasps and lacewings, to name a few!). These can be attracted into the garden by planting a selection of indigenous plants, incorporating an insect hotel, or by letting some bits of the garden grow wild.

Chemical treatment

Wherever possible, aphids should be tolerated on plants because they are food for other wildlife. Aphid populations tend to peak during spring, but die off when natural enemies become more apparent later in the summer. For outdoor plants, assess the level of damage for the time of year before taking action with chemicals When using chemicals, it’s always best to act when nymphs (immature aphids) are most active, which tends to be in the spring. Assess the plants' size. Full pesticide coverage for trees and large shrubs is expensive, if not impossible, to achieve. Likewise, apply pesticides before flowering occurs. Sprays can be indiscriminate killers, killing the useful insects as well as the bad. Killing the beneficial insects can make pest problems worse in the years to come! Contact insecticides containing natural plant oils can be more environmentally benign than synthetic pesticides. Look out for products containing natural pyrethrums, fatty acids and plant oils. Any product containing oil should be applied during colder periods of the day. Synthetic pyrethroids that are available for home use include ingredients: deltamethrin, lambda-cyhalothrin and cypermethrin. These can be applied less frequently. Likewise, if you intend to eat your crop, be sure it is listed on the bottle and follow directions carefully.

Attracts

Aphids possess a broad host range, making them common pests in gardens!

Repels

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Knowledge and advice

Search our ever-growing knowledge base to find plants and information. Find out about pests and diseases you should be keeping an eye out for. Watch How to videos or follow step by step guides for tasks in the garden. Free download for your phone or tablet.
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