As the weather warms up, garden pests come into their own. This month we turn our attention to aphids. Ignore this pest at your peril.
The aphid can wreak havoc in two ways. Firstly it’ll cause direct damage to the plant by draining vital cell sap through its needle-like mouthpart, and secondly it’s a known carrier of plant viruses. They are found clustered all over the growing tip of a plant, where it’s easier to feed on fresh new cells.
There are two words associated with the aphid that should strike fear in every gardener’s heart. Parthenogenesis and viviparity: known in the bug trade as P & V, and the aphid is both
Parthenogenesis means that reproduction of progeny can occur without fertilisation, or put another way a female doesn’t need the services of a male to produce offspring.
Viviparity is the ability to produce live young, without having to lay eggs to hatch out later. And the news gets worse: In cool weather full reproduction might take 21 days but when it’s hot, it’s job done in around 8! One single aphid can become a million in a flash..
Aphids are also known as blackfly or greenfly, and they can also be yellow, grey, brown or pink. All aphids will look similar in appearance.
Dealing with the aphids outdoors
- vigilance: catch them early before the population explodes in your back garden. Avoid giving plants too much nitrogen rich fertiliser as this encourages the lush growth that aphids love
- wipe young aphids off with your finger and thumb
- prune out any aphid infested shoots, and put them into the dustbin
- Allow Nature to lend a helping hand. The ladybird, hoverfly and lacewing are particularly partial to aphids and will help clean up for you.
To encourage these natural predators, stop using pesticides round the garden and grow the plants that they love best such as poached egg plant and calendulas. The ladybird adult is quite distinctive, but alas its black and yellow knobbly larvae is often mistaken for some fiendish pest and exterminated.
- Spray with insecticidal soap and water. I suppose this is a modern interpretation of Victorian ladies chucking their washing up water over the roses. The soap isn’t poisonous, it merely strips off the waxy covering from the pest so that the little darlings dehydrate to death.
- Protection. By spraying with a systemic insecticide you’ll achieve two things. Firstly, the chemical will kill on contact with any insect that happens to be on the plant. Secondly, the active ingredient is absorbed by the plant and drawn into the cell sap so any feeding sap sucker that stops for sustenance is killed off on feeding.
Auntie Planty is a qualified horticulturist who offers plant health checks and gardening lessons in your own garden. Her advice is only a phone call away.
© 2009 Valerie McBride-Munro