Aphids, Blackfly, Greenfly, Plant Aphids
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One of the most common garden pests, aphids are small sap-sucking insects in the superfamily Aphidoidea. They are often seen feeding in clusters on new plant growth. There are over 4000 species worldwide and in low to moderate numbers, they are generally not too harmful to plants. 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.
Aphids produce large amounts of honeydew. This sticky fluid drips on plants and attracts ants and can also promote sooty mold growth on leaves.
Aphids are a source of food, especially for ladybugs and lacewings.
Aphids may be green, brown, yellow, black or red in colour depending on species and their food source. They are rather small and have pear-shaped bodies that are soft. Some may have a waxy or woolly coating and are known as 'Woolly aphids'.
Colonies of aphids clustered on young stems, leaves and buds Wilting and distortion of leaves and young shoots Yellowing and premature death of leaves and young plants A sticky substance on the plant or leaves, known as honeydew
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 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. 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 the garden grow wild.
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. 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. 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. Synthetic pyrethroids that are available for home use include ingredients: Deltamethrin, lambda-cyhalothrin and cypermethrin. These can be applied less frequently.