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How to identify it
- Wingless adults are shiny black and larger than the other aphids found on citrus. Nymphs are red-brown or gray.[1]
- Check the legs: the 'knees' of all three pairs are very dark. The antennae are not striped, but roughly the outer half of each is dark.[1]
- The siphunculi (the two tailpipes on the rear of the abdomen) are only slightly longer than the cauda (the tail).[1]
- Winged adults are the easiest to recognize, with conspicuously black first, second and third antennal segments, but they are seen less often because they leave the colony soon after they develop.[1]
- Colonies sit on tender new leaves and flower flush, often mixed with other aphid species, so a hand lens helps.[1][3]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Black citrus aphid | Black citrus aphid adults are matte rather than shiny black, and their antennae look striped because the joints between segments are dark.[1] |
| Melon (cotton) aphid | Melon aphid is also dark and also carries citrus tristeza virus, but it is mottled rather than shiny black, its tail is much paler than its tailpipes, and its 'knees' are pale.[1][2] |
| Cowpea aphid | Cowpea aphid usually has dark 'knees' only on the hind legs, only about a third of the antenna is dark, and its tailpipes are much longer than the tail. The two can't always be separated in the field.[1] |
| Spirea (green citrus) aphid | Spirea aphid is yellow or green, not black.[1] |
Where it lives
Native to tropical Southeast Asia, it has spread to most citrus-growing areas worldwide, including Africa south of the Sahara, Australia, South America and the Caribbean, but not California or the Mediterranean basin apart from Madeira and northwestern Iberia. In Florida it was first found in Dade and Broward counties, mostly on dooryard trees; UF's current citrus guide says it has become rare there, possibly because of intense spraying for psyllids.[3][1][2]
Biology and life cycle
It feeds and reproduces on the tender new leaves and flower flush of citrus and a few close relatives. Reports from plants outside the citrus family are uncertain.[3][1][2]
In most of the world there are no males and no eggs: every aphid is a female that gives birth to live young. Japan is an exception, with a sexual generation on citrus.[1][3]
Populations can explode. Nymphs mature in six to eight days at 20 C (68 F) or warmer, and one aphid could in theory give rise to more than 4,400 in three weeks if nothing ate them.[1]
Winged forms are produced as the colonized new growth matures. Because the aphid has such a narrow host range, a winged aphid leaving one citrus tree is likely to feed next on another citrus tree.[1]
Damage and signs
- Heavy colonies on new flush do direct damage, and their honeydew grows sooty mold that blocks light from the leaves.[1][2]
- It is the most efficient vector of citrus tristeza virus, six to 25 times as efficient as the melon aphid, which was Florida's main vector before it arrived. It also transmits some virus strains other aphids can't.[1][2][3]
- Tristeza causes quick decline in trees on sour orange rootstock, which often die suddenly with fruit still on them. After the aphid reached Brazil and Argentina, the virus killed 16 million trees on sour orange rootstock.[2][1]
Health risk
The sources treat it only as a citrus pest; none mentions bites or any risk to people or pets.[1][2][3]
Control
Prevention
Plant only certified, disease-free citrus nursery stock and budwood: people moving infected plants spread tristeza faster and farther than any aphid. Where the aphid is established, growers move away from sour orange and other tristeza-susceptible rootstocks.[1]
Sanitation
Abandoned or volunteer citrus and urban dooryard trees can act as reservoirs of the aphid and the virus, and most aphid flight is local, so nearby sources matter most.[1]
Biological control
Lady beetles, hoverflies, lacewings and other natural enemies normally keep aphids on citrus flush below damaging levels. Parasites, predators and fungal diseases attack the brown citrus aphid too, though how much they suppress it isn't well known.[2][1]
Pesticides
Mature citrus trees sustain little aphid damage and shouldn't need treatment. Florida's guide reserves treatment for young groves under three years old with more than half of the expanding shoots infested; soil-applied systemic insecticides work only as prevention because the tree takes time to absorb them. It isn't known whether spraying aphids slows the spread of tristeza, but insecticides may help protect nursery stock and budwood sources.[2][1]
Common questions
- How do I know if the black aphids on my citrus are brown citrus aphids?
- Look for shiny black wingless adults with very dark 'knees' on all six legs and the outer half of each antenna dark, or winged adults with black inner antennal segments. Matte black aphids with striped antennae are black citrus aphids, and mottled ones are probably melon aphids.[1][2]
- Is the brown citrus aphid in California?
- EFSA's 2018 assessment lists California, along with the Mediterranean basin, as one of the citrus regions it had not spread to.[3]
- Why is the brown citrus aphid so dangerous to citrus?
- It spreads citrus tristeza virus far more efficiently than other aphids, and the virus can kill trees on sour orange rootstock quickly.[1][2][3]
Sources
- University of Florida IFAS Extension (EDIS), “Brown Citrus Aphid, Toxoptera citricida (Featured Creatures EENY-007, S.E. Halbert and L.G. Brown, 1996; archival copy).” journals.flvc.org/edis/article/view/138493 (accessed 2026-11-09)
- University of Florida IFAS Extension (EDIS), “2026-2029 Florida Citrus Production Guide: Soft-Bodied Insects Attacking Foliage and Fruit (CPG vol. 1 ch. 24).” journals.flvc.org/edis/article/view/133504 (accessed 2026-11-09)
- European Food Safety Authority (EFSA Journal), “EFSA Panel on Plant Health. Pest categorisation of Toxoptera citricida. EFSA Journal 16(1):5103 (2018) (abstract).” doi.org/10.2903/j.efsa.2018.5103 (accessed 2026-11-09)
- iNaturalist, “Aphis citricidus taxon page (order and family).” www.inaturalist.org/taxa/1609507 (accessed 2026-11-09)