Otherwise known as greenfly and blackfly, these sap-sucking garden pests feed on all foliage and flowers and are particularly partial to ornamental plants, fruit, vegetables and houseplants. Aphids cause distorted growth and excrete a sticky substance that attracts a growth of sooty mould on garden plants, fruits and vegetables.
Aphids can be carried for hundreds of miles by wind or air currents and can transfer viruses to other plants, notably strawberries, raspberries, tomatoes, dahlias and sweet peas.
How to spot aphids
You should be able to see aphids on plants without a magnifying glass; look out for their pear-shaped bodies and thin spindly legs and pipes called ‘cornicles’ at the bottom of their abdomen. If you notice distorted new growth on your plants, this is likely to be the work of aphids.
There are more than 500 aphid species in Britain. The most common aphid species are green or black, but there are also species that are yellow, pink, white or mottled. Some aphids cover themselves with a white waxy secretion which can be confused with some scale insects, mealybug or whitefly.
Be on the lookout for them from spring to late summer outdoors, and all year round indoors. They are commonly found on roses and can build up into big colonies if left unnoticed.
How to treat aphids
You can squash small infestations of aphids on plants with your fingers or blast with a jet of water. If the infection is limited to a few plants, you can use horticultural soft soap or a very diluted solution of washing up liquid to wash off aphids from leaves and buds. If the infection is major, this can be tedious and can cause leaf damage.
For a more holistic approach, encourage natural predators such as ladybirds, hoverfly and lacewing into your garden by planting nectar-rich flowering plants such as wallflowers, sweet williams and African marigolds. Nettles are also good to plant as they attract the nettle aphid, which is a good source of food for lots of aphid eating insects.
Nettle aphids also appear early in the year, so they attract the predators early on in the season and won’t attack your precious plants as they only feed on nettles. Another solution is to try a biological control such as ladybird or lacewing larvae.