EENY-042
Citrus Blackfly, Aleurocanthus woglumi Ashby (Insecta:
Hemiptera: Aleyrodidae) 1
Ru Nguyen, Avas B. Hamon, and Thomas R. Fasulo 2
1. This document is EENY-042, one of a series of the Entomology and Nematology Department, UF/IFAS Extension. Original publication date July 1998.
Revised April 2016. Reviewed February 2019. Visit the EDIS website at https://edis.ifas.ufl.edu for the currently supported version of this publication.
This document is also available on the Featured Creatures website at http://entomology.ifas.ufl.edu/creatures .
2. Ru Nguyen; Avas B. Hamon, Florida Department of Agriculture and Consumer Services, Division of Plant Industry, and Thomas R. Fasulo, Department
of Entomology and Nematology; UF/IFAS Extension, Gainesville, FL 32611.
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county’s UF/IFAS Extension office. U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.
Introduction
While the citrus blackfly, Aleurocanthus woglumi Ashby
(Figure 1), is a serious citrus pest of Asian origin (Dietz and
Zetek 1920), it is usually under effective biological control
in Florida. Although a member of the whitefly family, the
adult of this species has a dark, slate blue appearance that
led to it being given the name “blackfly.”
Distribution
Citrus blackfly was discovered in the Western Hemisphere
in 1913 in Jamaica. It spread to Cuba in 1916, Mexico in
1935 (Smith et al. 1964), and was detected in Key West,
Florida, in 1934. It was eradicated from Key West in 1937
(Newell and Brown 1939). Rediscovered in Ft. Lauderdale,
Florida in 1976 (Dowell et al. 1981), citrus blackfly was
detected in Palm Beach and Miami-Dade counties in 1977;
Lee, Highlands, and Brevard counties in 1979; Manatee
County in 1986; Polk County in 1989; Marion and Volusia
counties in 1991; and Alachua County in 1992 (Nguyen,
unpublished data). At present, it is widely spread from
north-central through south Florida.
Description and Life History
The life cycle from egg to adult ranges from 45 to 133 days,
depending on the temperature (Dietz and Zetek 1920). Six
generations per year are produced in south Florida (Nguyen
et al. 1983).
Egg
The egg is laid with other eggs in a spiral pattern on the
underside of the leaf. Each female lays two to three egg-
spirals during her 10 to 14-day lifespan. Eggs hatch within
seven to 10 days (Dowell et al. 1981).
Figure 1. Citrus blackfly, Aleurocanthus woglumi Ashby, egg spiral and
first instars.
Credits: Division of Plant Industry
2 Citrus Blackfly, Aleurocanthus woglumi Ashby (Insecta: Hemiptera: Aleyrodidae)
Nymph
The first instar is elongate-oval, averaging 0.30 mm long
by 0.15 mm wide and is brown in color, with two glassy
filaments curving over the body. The first instar lasts seven
to 16 days. The second instar is more ovate and convex than
the first instar, averaging 0.40 mm long b 0.20 mm wide,
and is dark brown in color with numerous spines covering
the body. The second instar lasts seven to 30 days. The third
instar is more convex and much longer than the second,
averaging 0.87 mm long by 0.74 mm wide. The body is a
shiny black with spines stouter and more numerous than
those in the second instar. The third instar lasts six to 20
days (Dietz and Zetek 1920, Smith et al. 1964).
Pupa
The fourth instar, or so-called pupa case, is ovate and a
shiny black with a marginal fringe of white wax (Figure 2).
The sex is readily distinguishable. Females average 1.24 mm
long by 0.71 mm wide; males are 0.99 mm long by 0.61 mm
wide. The pupal stage lasts 16 to 50 days (Dietz and Zetek
1920, Dowell et al. 1981).
Adult
The adult emerges from a T-shaped split appearing in the
anterior end of the pupal case. At emergence, the head is
pale yellow, legs are whitish, and eyes are reddish-brown
(Figure 3). Within 24 hours after emergence, the insect is
covered with a fine wax powder, which gives it a slate blue
appearance (Dietz and Zetek 1920).
Identification
The identification key provided here is designed to identify
the four major species of whiteflies that commonly infest
citrus in Florida. Another key that covers 16 species of
whiteflies that may infest Florida citrus is available on
the Internet. That, developed by the Florida Department
of Agriculture and Consumer Services’ Division of Plant
Industry, uses color photographs of nymphs to assist in
identification. It is available at http://www.freshfromflorida.
com/Divisions-Offices/Plant-Industry/Science/Key-to-
Whitefly-of-Citrus-in-Florida/Key-To-Whitefly-On-Citrus-
In-Florida/I.-Key-To-Whitefly-Fourth-Instars-On-Citrus
1a. The whitefly adult is white or white with dark spots on
the wings. Nymphs are difficult to see or identify. . . . . 2
1b. The whitefly adult is slate blue in color, eggs are present
and laid in spirals. Nymphs are black with prominent
spines. . . . . citrus blackfly
2a. The whitefly adult is all white without any dark spots on
wings. . . . . citrus whitefly
2b. The whitefly adult is white with a darkened area at the
end of each wing. Occasionally a yellow fungus is present. .
. . . cloudywinged whitefly
2c. The whitefly female adult is all white and is surrounded
by waxy filaments. Eggs are laid in a circle with the female
at rest in the center. . . . . woolly whitefly
Economic Importance
Citrus blackfly infests over 300 host plants, but citrus is the
most suitable for large population development (Figure 4).
It damages citrus by sucking nutrients from foliage, which
weakens the plants. Citrus blackflies excrete honeydew on
which sooty molds develop. Sooty molds coat citrus leaves,
causing them to appear black. Sooty molds can severely
impair leaf respiration and photosynthesis.
Figure 2. Pupae of citrus blackfly, Aleurocanthus woglumi Ashby.
Credits: Division of Plant Industry
Figure 3. Adult citrus blackfly, Aleurocanthus woglumi Ashby.
Credits: Division of Plant Industry
3 Citrus Blackfly, Aleurocanthus woglumi Ashby (Insecta: Hemiptera: Aleyrodidae)
While this species is found in very low numbers in most
groves, it is normally under effective biological control and
pest populations rarely require treatment (Browning et al.
2006).
Management
Biological control: Citrus blackfly has several natural
enemies. In Florida, the most effective agents for control -
ling citrus blackfly are the parasitic wasps, Encarsia perplexa
Huang & Polaszek (Huang and Polaszek 1998) and Amitus
hesperidum Silvestri (Hart et al. 1978). A female citrus
blackfly larva will support two, and occasionally three or
four, parasites while a male citrus blackfly larva will support
only one parasite.
Development of Amitus hesperidum (Figure 5) is synchro -
nized with its host, in that adult female parasites are ready
to lay eggs when the susceptible larval stages of citrus
blackfly are present. Each female parasite can produce up
to 70 offspring in four to five days with adequate hosts
available. Female Amitus hesperidum lay eggs in all three
larval stages of citrus blackfly, with a preference for the first
stage. However, this parasite has poor searching ability and
a short lifespan. Amitus hesperidum is most effective with
high density citrus blackfly populations, especially during
cool temperature and high humidity seasons. An Amitus
hesperidum population will expire soon after suppression of
the citrus blackfly population (Nguyen et al. 1983).
Encarsia perplexa (Figure 6) has a lower rate of reproduc -
tion than Amitus hesperidum , but has better searching
ability. Generally, Encarsia perplexa can maintain a citrus
blackfly population at a lower level than Amitus hesperidum .
Mated females of Encarsia perplexa lay a single diploid egg
in any larval stage of the host, although the second stage
appears preferable. This egg will produce a female parasite.
Figure 4. Heavy infestation of citrus blackfly, Aleurocanthus woglumi
Ashby, on citrus leaves.
Credits: Division of Plant Industry
Figure 5. A) Pupae of citrus blackfly, Aleurocanthus woglumi Ashby, and
the adult parasitoid, Encarsia perplexa Huang & Polaszek, and B) Pupal
cases of the citrus blackfly, Aleurocanthus woglumi Ashby, from which
the parasitoid has emerged. Egg spirals of the citrus blackfly are also
evident.
Credits: Division of Plant Industry
Figure 6. A) Adult Encarsia perplexa Huang & Polaszek, and (B) pupal
cases of the citrus blackfly, Aleurocanthus woglumi Ashby, from which
the parasitoid has emerged.
Credits: Division of Plant Industry
4 Citrus Blackfly, Aleurocanthus woglumi Ashby (Insecta: Hemiptera: Aleyrodidae)
Adult females may survive up to six weeks. Virgin female
Encarsia perplexa may deposit a haploid egg in a fully-de -
veloped female larva of Encarsia perplexa (her own species),
and this egg will produce a male parasite (adelphoparasite).
The sex ratio in the field is 1:7 (male:female) (Smith et al.
1964, Nguyen 1987).
Chemical control: Whiteflies also are controlled by sprays
applied primarily for control of scale insects. Spraying of
commercial citrus exclusively for whitefly control is seldom
practiced in Florida. Recommended control measures for
commercial or dooryard citrus are significantly different.
Please consult the specific management guide, Florida
Citrus Management Guide for Whiteflies in Commercial
Groves , for your situation.
It is important to note that spraying with copper for control
of harmful fungal diseases will inhibit growth of “friendly
fungi” resulting in an increase in whitefly populations. Also,
more than one application of sulfur per year can have an
adverse effect on parasites. Spray oil has some insecticidal
properties, but is primarily used to remove sooty mold that
grows on the fruit and leaves.
Selected References
Browning HW, Childers CC, Stansly PA, Peña J, Rogers ME.
(November 2008). 2009 Florida citrus pest management
guide: soft-bodied insects attacking foliage and fruit . EDIS .
ENY-604. (1 July 2013)
Dietz HF, Zetek J. 1920. The blackfly of citrus and other
subtropical plants. USDA Bulletin 885: 1-55.
Dowell RV, Cherry RH, Fitzpatrick GE, Reinert JA, Knapp
JL. 1981. Biology, plant-insect relations, and control of the
citrus blackfly. Florida Agricultural Experiment Station
Bulletin 818: 1-48.
Hamon AB. (1997). Whitefly of citrus in Florida. FDACS.
(no longer available online).
Hart WG, Selhime A, Harlan DP, Ingle SJ, Sanchez-R M,
Rhode RH, Garcia CA, Caballero J, Garcia RL. 1978. The
introduction and establishment of parasites of citrus black -
fl y, Aleurocanthus woglumi in Florida (Hem.: Aleyrodidae).
Entomophaga 23: 361-366.
Huang J, Polaszek A. 1998. A revision of the Chinese
species of Encarsia Forster (Hymenoptera: Aphelinidae):
parasitoids of whiteflies, scale insects and aphids
(Hemiptera: Aleyrodidae, Diaspididae, Aphidoidea).
Journal of Natural History 32: 1825-1966.
Newell W, Brown AC. 1939. Eradication of the citrus
blackfly in Key West, Fla. Journal of Economic Entomology
32: 680-682.
Nguyen R. 1987. Encarsia opulenta (Silvestri) a parasite of
Aleurocanthus woglumi Ashby (Hemiptera: Atherinidae).
Florida Department of Agriculture & Consumer Services,
Division of Plant Industry. Entomology Circular 301. 2 pp.
Nguyen R, Brasil JR, Poucher C. 1983. Population density
of the citrus blackfly, Aleurocanthus woglumi Ashby (Ho -
moptera: Aleyrodidae), and its parasites in urban Florida in
1979-81. Environmental Entomology 12: 878-884.
Smith HD, Maltby HL, Jimenez EJ. 1964. Biological control
of the citrus blackfly in Mexico. USDA-ARS. Technical
Bulletin No. 1311: 1-30.
