Skip to main content

FACTSHEETS FOR FARMERS
www.plantwise.orgCreated in Zambia, July 2015

Ladybirds to control aphids in cotton

Recognize the problem

Cotton (Butonje in Tonga) is often attacked by aphids (njina in Tonga, inda in

Nyanja). The aphids are tiny greenish or blackish, soft insects that can have

wing or no wings. They are so small so that you can only just see them. They

often sit in groups on the underside of cotton leaves (= aphid colonies). There

they suck sap out of the leaves. Leaves curl and later become yellow.

Background

When farmers see aphids, they start spraying, often every two weeks, which

means that pest scouting (kulangalanga tuuka in Tonga) is not done. However,

cotton plants can tolerate low levels of aphids and there are many natural

enemies that can control these aphids, such as lacewing larvae or ladybird

beetles or their larvae. However, these are killed by the by insecticide sprays

which then causes the aphids to become an even bigger problem because they

can multiply quickly. 1 aphid can produce up to 10 young per day.

Ladybird beetles are usually orange or red with black or light coloured spots on

the wing covers but the colour can vary and some can be even black. Ladybird

beetles are roundish, hard covered and shiny. Its larvae are black with yellow

spots and 6 clearly seen legs. Ladybird larvae can feed on 50 adult aphids in 2

days, thus about 500 aphids in 3 to 4 weeks. Ladybirds also eat aphid eggs.

Ladybird beetles are farmer friends that can control aphid population without

the use of chemicals which will help reduce the cost of growing cotton.

Management

• Scout for aphid colonies as well as ladybird beetles and larvae by walking

across the field and checking 10 to 20 plants at a distance of 5 paces

between plants. Do this in at least 3 areas of your field.

• Check the lower leaf, then the middle leaf and the top of the plant.

Ladybirds are often near aphid colonies.

• Record the numbers of aphid colonies if possible, and/or the number of

ladybird beetles and larvae per plant.

• If you find 1 ladybird beetle or larvae every 2nd or 3rd aphid

colony (this means per about 50 to 100 aphids), usually no

chemical spray is needed.

• Continue scouting every 1 to 2 weeks to check on aphids and ladybirds.

• If aphid populations still increase enormously, only then should chemical

sprays be considered.

Scientific name(s) > Aphis gossypii

The recommendations in this factsheet are relevant to: Zambia

Authors: George Edward Silumbwe

Ministry of Agriculture & Livestock

tel: 0961189769 email: edwardgeorgesilumbwe@gmail.com

Edited by Plantwise

Plantwise is a global initiative led by CABI

ZM048En

Lose Less, Feed More

1 to 2 mm small aphids on the

underside of the leaf. (Photo by

Scot Nelson)

Ladybird beetle (1/2 cm) feeding

on aphids. (Photo by Dave

Campbell, CC BY NC ND)

x

Please add some content in Animated Sidebar block region. For more information please refer to this tutorial page:

Add content in animated sidebar