Egg: Eggs are laid in a spiral pattern on the underside of the leaf. Each female lays two to three egg-spirals during her 10 to 14 day life span. Eggs hatch within seven to 10 days (Dowell et al. 1981).
Nymph: The first instar is elongate-oval, averaging 0.30 mm long x 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 x 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 x 0.74 mm wide. The body is 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 shiny black with a marginal fringe of white wax. The sex is readily distinguishable. Females average 1.24 mm long x 0.71 mm wide; males are 0.99 mm long x 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. 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).
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
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).
Development of A. hesperidum is synchronized 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 A. 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 life span. A. hesperidum is most effective with high density citrus blackfly populations, especially during cool temperature and high humidity seasons. An A. hesperidum population will expire soon after suppression of the citrus blackfly population (Nguyen et al. 1983).
Encarsia perplexa has a lower rate of reproduction than A. hesperidum, but has better searching ability. Generally, E. perplexa can maintain a citrus blackfly population at a lower level than A. hesperidum. Mated females of E. 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. Adult females may survive up to six weeks. Virgin female E. perplexa may deposit a haploid egg in a fully-developed female larva of E. 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 for your situation.
Florida Citrus Management Guide for whiteflies in commercial groves
It is important to note that spraying with copper for control of harmful fungal diseases will also 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 which grows on the fruit and leaves.
Authors: Ru Nguyen and Avas B. Hamon, Florida Department of Agriculture and Consumer Services, Division of Plant Industry; and Thomas R. Fasulo, University of Florida
Originally published as DPI Entomology Circular 360. Updated for this publication.
Photographs: Division of Plant Industry
Project Coordinator:
Thomas R. Fasulo, University of Florida
Publication Number: EENY-42
Publication Date: July 1998. Latest revision: March 2010.
Copyright 1998-2010 University of Florida
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Department of Entomology and Nematology
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egg spiral and first instars
pupae
adult
heavy infestation
Amitus hesperidum
Encarsia perplexa