Citrus aphids

Date: 2022   Author: Jianhua Mo

Figure 1. Typical aphid infested flush. Photo: Nerida Donovan.

Species

Several species of aphids are found on citrus including:

  • black citrus aphids (Toxoptera aurantii and Toxoptera citricida, note, the latter is sometimes called brown citrus aphid; Figure 2 and 3)
  • melon aphid (Aphis gossypii; Figure 4)
  • spiraea aphid (Aphis spiraecola; Figure 5 and 6).

Figure 2. Toxoptera aurantii infestation in citrus. Photo: Kavous Ayazpour, iNaturalist.

Figure 3. Toxoptera citricida infestation in citrus. Photo: JW Lotz, Florida Department of Agriculture and Consumer Services, Bugwood.org.

Figure 4. Aphis gossypii nymphs and adults. Photo: Clemson University, USDA Cooperative Extension Slide Series, Bugwood.org.

Figure 5. Aphis spiraecola colony. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org.

Figure 6. Honeydew excreted by Aphis spiraecola colony. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org.

Description

Aphids are small (about 2 mm long), soft-bodied insects with characteristic tubular extensions to the abdomen. Adults can be winged or unwinged. Aphids have complex life cycles; when conditions are good, the females can reproduce asexually, then during winter, they can reproduce sexually (Figure 7). Aphids can build up large populations quickly. However, in environments undisrupted by pesticide use, aphids are normally kept at low levels by a suite of beneficial insects.

Figure 7. The general aphid life cycle. Asexual reproduction occurs during most of the year (summer cycle). Some aphid species produce a generation of sexual individuals that produce overwintering eggs as shown in the winter cycle. Source: University of California.

Damage

Aphids feed on plant sap using their sucking mouthparts, distorting shoots and transmitting plant viruses. They also produce honeydew, which encourages sooty mould growth.

Monitoring

Check young shoots in early September and late October for spring flush, and February to April for summer–autumn flush. Examine 5 to 10 young leaves from each shoot for aphids, honeydew and sooty mould.

Natural predators

  • Parasitic wasps: Aphidius spp. (Figure 8 and 9) and Aphelinus spp. (Figures 10–12)
  • Predatory lady beetles: Coccinella transversalis (Figure 13), or the transverse lady beetle, is native to Australia.
  • Lacewings (Figures 14–18)
  • Syrphid flies (Simosyrphus grandicornis; Figures 19 and 20) are an Australasian species of hoverfly.

Figure 8. Aphidius sp. adult. Photo: David Cappaert, Bugwood.org.

Figure 9. Mummies left after Aphidius colemani young hatch inside the aphid and eat their way out. Photo: Nick Dimmock, University of Northampton, Bugwood.org.

Figure 10. Aphelinus sp. adult. Photo: Frank Peairs, Colorado State University, Bugwood.org.

Figure 11. Aphelinus sp. adult. Photo: Frank Peairs, Colorado State University, Bugwood.org.

Figure 12. Aphid mummies after parasitisation by Aphelinus sp. Photo: Frank Peairs, Colorado State University, Bugwood.org.

Figure 13. Coccinella transversalis adult. Photo: Sonya Broughton, Department of Agriculture & Food Western Australia, Bugwood.org.

Figure 14. Brown lacewings (Micromus sp.) adult. Photo: David Cappaert, Bugwood.org.

Figure 15. Brown lacewings (Micromus sp.) larva. Photo: David Cappaert, Bugwood.org.

Figure 16. Brown lacewings (Hemerobius sp.) pupa. Photo: Bradley Higbee, Paramount Farming, Bugwood.org.

Figure 17. Green lacewing (Chrysoperla rufilabris) adult. Photo: Joseph Berger, Bugwood.org.

Figure 18. Green lacewing (Mallada signata) larva feeding on Toxoptera citricida. Sonya Broughton, Department of Agriculture & Food Western Australia, Bugwood.org.

Figure 19. Simosyrphus grandicornis adult. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org

Figure 20. Simosyrphus grandicornis larva feeding on aphids. Photo: Clemson University, USDA Cooperative Extension Slide Series, Bugwood.org.

Control measures

  • Control measures are needed only when 25% or more of leaf flushes are infested and when the presence of beneficial insects on infested shoots is less than 25%.
  • Appropriate actions include spraying young growth with a specific aphicide.
  • Check the APVMA PubCRIS database for registered controls.
Always read the label

Users of agricultural (or veterinary) chemical products must always read the label and any Permit before using the product, and strictly comply with the directions on the label and the conditions of any Permit. Users are not absolved from compliance with the directions on the label or the conditions of the Permit by reason of any statement made or not made in this publication.

Warning

Pesticide residues may occur in animals treated with pesticides, or fed any crop product, including crop waste, that has been sprayed with pesticides.

It is the responsibility of the person applying a pesticide to do all things necessary to avoid spray drift onto adjoining land or waterways.