Key to Whitefly of Citrus in Florida (Homoptera: Aleyrodidae)

Created by Avas B. Hamon

Greg Hodges, Greg.Hodges@FreshFromFlorida.com, Taxonomic Entomologist, Florida Department of Agriculture and Consumer Services, Division of Plant Industry

CONTENTS: This is a field key to aid in identifying species of whiteflies that occur on citrus in Florida. I hope it is helpful to those with an interest in whiteflies on their citrus.

INTRODUCTION: The family Aleyrodidae is composed of tiny insects which obtained the common name "whiteflies" because the wings and bodies of the adults are covered with a fine, powdery or flour-like white wax. Thus the adults resemble tiny moths with which they might be confused. In fact, early workers thought they were minute moths. The eggs are almost invariably attached to the underside of leaves, by means of a short or long stalk. Their surfaces may be smooth or sculptured (honeycombed). Many species lay their eggs in one or more semicircular or circular concentric rows, but others scatter their eggs over the leaf. The first stage is usually pale in color, somewhat translucent with well developed legs and antennae. After emerging they crawl around for a short time before selecting a site to feed. All of the following stages are spent in the same spot. The usual number of larval stages is four. The so called pupal cases of many species exhibit varying amounts of wax secretion from papillae, simple pores, or compound pores.

The adults leave the pupal case through the inverted T-slit in the dorsum. Immediately after emergence, the adults of many species begin to feed, even before the wings are unfolded. Both males and females are winged, having 4 membranous wings without cross veins. There is sexual dimorphism only to the extent of differences in genitalia, slight differences in male antennae, and in the slightly smaller size of the male. Most species of whiteflies have more than one generation each year and in the warmer areas continuous generations probably occur with slowed development during short, cool periods. Like aphids and scale insects whiteflies are often attended by ants. In at least one species it appears essential for ants to collect the honeydew or the whiteflies become overgrown by a fungus.

On a worldwide basis more than 65 species of whitefly are reported as ocuring on Citrus spp. Several species of whiteflies are economically important. The greenhouse whitefly, Trialeurodes vaporariorum, occurs over most of the U.S. and is a pest in northern greenhouses, but occurs outdoors in the southern states. The citrus whitefly, Dialeurodes citri; cloudy-winged whitefly, D. citrifolii; and woolly whitefly, Aleurothrixus floccosus, are common on citrus in Florida. In 1976 the citrus blackfly, Aleurocanthus woglumi, was found in Florida. Generally, whitefly populations are kept in check by natural parasites and predators, but in agriculture crops or on ornamentals, where man has upset the natural balance, consistent high and often damaging populations may occur.

COLLECTING WHITEFLIES: When collecting whiteflies always attempt to obtain a fairly large series. If possible collect all stages including the adult. Sometimes adults can be obtained (reared) from pupae, if the pupae are collected at the correct time. The taxonomy of whiteflies is largely based on pupal (fourth instar skin) characters., but it is good to have supplemental information for all stages, so a sound taxonomy can be developed.

Whitefly keys

REFERENCES

  • Back, E. A. 1910. The woolly whitefly: A new enemy of the Florida orange. U.S.D.A., Bur. Entomol. Bull. No. 64. VIII:65-71.
  • Ebling, W. 1959. Subtropical fruit pests. Univ. Calif. 436 pp.
  • Morrill, A. W., and E. A. Back. 1911. Whiteflies injurious to citrus in Florida. USDA Bur. Entomol. Bull. 92:1-109.
  • Mound, L.A. 1963. Host-correlated variation in Bemesia tabaci (Gennadius) (Homoptera: Aleyrodidae). Proc. R. ent. Soc. London. (A)38:171-180.
  • Mound, L.A. 1973. Chapter 13. Thrips and Whitefly. Pp. 229-242. in Gibbs, A.J. Viruses and invertebrates. 673 pp. Amsterdam and London.
  • Mound, L. A., and S. H. Halsey. 1978. Whitefly of the world. A systematic catalogue of the Aleyrodidae (Homoptera) with host plant and natural enemy data. British Mus. Nat. Hist., Chichester. 328 pp.
  • Quaintance, A.L., and A.C. Baker. 1913. Classification of the Aleyrodidae Part I. Tech. Ser. Bur. Ent. U.S. 27. 93pp.
  • Quaintance, A. L., and A. C. Baker. 1916. Aleyrodidae, or white flies attacking the orange, with description of three new species of economic importance. J. Agr. Res. 6:459-72.
  • Russell, L. M. 1965. A new species of Aleurodicus Douglas and two close relatives (Homoptera: Aleyrodidae). Fla. Entomol. 48:47-55.
  • Russell, L. M. 1964. Dialeurodes kirkaldyi (Kotinsky), a whitefly new to the United States (Homoptera:Aleyrodidae). Fla. Entomol. 47:1-4.
  • Russell, L. M. 1948. The North American species of whiteflies of the genus Trialeurodes. U.S.D.A. Misc. Pub. 635;1-85.
  • Weems, H.V. Jr, 1971. Aleurodicus dispersus Russell (Homoptera: Aleyrodidae), a possible vector of lethal yellowing disease of coconut palms. Fla. Dept. Agric. and Consumer Services. DPI Entomology Circular 111:1-2., illus.
  • Yothers, W. W. 1919. The woolly white fly in Florida citrus groves. U.S.D.A. Farmers Bull. 1011:1-14.

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Created: May 2001 | Updated: March 2006