Aphids - a major garden pest
Aphids are soft bodied insects which live on the sap of a wide number of plants.
You will find them on the underside of leaves, and also clustering around buds
and flowers. Aphids are generally greenish but can also be black, orange, or
shades of brown. The green aphids typically found on roses are usually called
"greenfly", and the fat black aphids often found on broad beans are called
Some Aphids have wings to fly in from outside and set up new Aphids colonies at
any time. Aphids multiply extremely fast during warm weather by producing live
young Aphids which already have the next Aphid generation developing inside
them when Aphids are born.
Look out for Aphids
Aphids are a few mm across, so you should be able to see them without a
magnifying glass. Look for little pear-shaped bodies with thin spindly
legs and pipes called "cornicles" at the bottom of their abdomen. They don't
move around very fast because they are usually in the process of feeding. Be
ready for aphids from Spring to Autumn, and don't let them build up big
colonies before it's too late.
of the more common species found in greenhouses include the green peach
aphid (Myzus persicae) which vary in colour from pale yellow to green to
pinkish-red and the melon or cotton aphid (Aphis gossypii) and the black bean
aphid (Aphis Fabae). There is also an aphid that specialises in brassicas
called the Mealy cabbage aphid (Brevicoryne
Aphids suck the sap out of the leaves and stems of the host plants, weakening
them and causing distortion to emerging flowers and leaves. Bad Aphid
infestations are very debilitating. The buds don't swell fully, and often the
flowers and fruit are small.
Because aphids feed directly on the sap they are thought to be responsible for
passing on viruses and other pathogens from plant to plant.
You won't be able to see any holes or bite marks because aphids feed by jabbing
their long sharp mouth parts into the soft parts of the plant and sucking out
the juices into their body.
Aphids excrete a sticky honeydew which turns black in damp conditions,
resulting in sooty mould. This blocks the leaf pores and cuts out light falling
on the leaves, apart from being quite unsightly.
To keep your aphid populations under control you need a number of weapons
in your armoury...
When to use
How to buy
||Aphidius are tiny flying insects which lay their eggs within the
aphid bodies and turn the dying aphid into a "mummy" which makes a useful nest
for hatching out more parasites
||Aphidius are the most popular, and least expensive way of controlling common
aphids, which is why they are the first choice for the commercial grower. Aphidius colemanii tend to tackle the smaller aphids such as Myzus persicae and Aphis gossypii - for
larger aphids there are Aphidius erivi
||More about aphidius
||Aphidoletes aphidimyza is a midge with predatory larvae that can control many aphid species. Adults are about 2mm long and lay eggs in colonies of aphids. Eggs hatch in 2-3 days and the orange-red larvae immediately start to search for aphids.
Larvae inject a poison into the aphid to paralyse it and dissolve the body contents.
The larvae take 7-16 days to mature before pupating in soil or compost and adults emerge after 10-14 days.
||The Aphid Midge will tackle a wide range of aphid species.
||More about aphidoletes
||Will catch and kill flying aphids
||Use sticky traps to monitor the aphid level and to catch a few when populations
||More about Sticky Traps
||Ladybirds love to consume aphids - particularly in summer.
||Adult ladybirds are quite capable of flying away and finding food elsewhere so
they are often supplied as larvae - long grey crawling insects that are not
nearly as attractive as their parents, Like all young adults, ladybird larvae
are extremely voracious feeders. Transporting ladybirds and larvae is a little
tricky because they are temperature sensitive and unless they have food they
eat each other - so there is inevitably a certain failure rate.
||More about ladybirds
||Lacewings (adults and larvae) also feed on aphids, and are slightly more
efficient than ladybirds.
||Lacewing larvae are actually called "aphid lions" - long grey crawling insects
that are not nearly as attractive as their parents, Like all young adults,
lacewing larvae are extremely voracious feeders. Do make sure that they have
enough to eat, because like many larvae they turn to cannabilism if they are
||More about lacewings
||Horticultural soft soap can be used to wash off aphids from leaves and buds
||If the infection is limited to a few plants you can carefully wash each leaf
with dilute soap. For larger infections use a dilute spray of this pure soap to get into shoots and flowers.
However keep the solution very dilute to avoid cell damage.
||More about soft soap
|SB Plant Invigorator
||SB Plant Invigorator is an insecticide made from plant extracts which stimulates plant growth as well as destroying insect pests.
||As with horticultural soap, the solution kills insects on contact by gumming up their wings and breathing apparatus.
||More about SBI
||Garlic Wonder is a dilute solution of garlic extract which acts as a deterrent and plant stimulant
||Garlic solutions are widely used commercially against aphids - they will not leave any residue on edible crops.
||More about Garlic Wash