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Publication #ENY-317

Whiteflies on Landscape Ornamentals1

E. A. Buss2

Whiteflies are common pests on many ornamental plants. Some of the most economically important species in Florida are the silverleaf whitefly, fig or ficus whitefly, citrus whitefly, and the rugose spiraling whitefly. The most frequently attacked plants include allamanda, avocado, chinaberry, citrus, fig, fringe tree, gardenia, gumbo limbo, ligustrum, mango, various palms, persimmon, viburnum, and many annuals.

Adult whiteflies (Figure 1) look like tiny white moths, but are more closely related to scale insects. Most are about 1/16 inch long and have four wings. The wings and body are covered with a fine white powdery wax. Reliable identifications are based on the adults. The immature whiteflies (nymphs) typically occur on the undersides of leaves, are flat, oval in outline, and slightly smaller than a pin head. Some species are light green to whitish and somewhat transparent (Figure 2). Others are black in the center and have a white waxy fringe around the edge.

Figure 1. 

Spiraling whitefly adult.


[Click thumbnail to enlarge.]

Figure 2. 

Giant whitefly adult and nymphs.


[Click thumbnail to enlarge.]

A generalized life cycle of the whitefly is as follows: The eggs are laid on the undersides of the leaves and hatch in 4 to 12 days into active, six legged nymphs (crawlers). The crawlers move around for several hours, then insert their mouthparts into the leaves and stay there. After molting three times, they pupate and then become adults. The pupal case remains on the plant tissue even after the adult has emerged. How long it takes for the insects to develop from eggs to adults varies from 4 weeks (summer) to 6 months (winter).

Whiteflies have piercing-sucking (needle-like) mouthparts with which they puncture the leaf and suck the plant fluids. The top sides of leaves on infested plants become pale or spotted due to these insects feeding on the undersides of the leaves. Oftentimes an infestation goes unnoticed until leaves turn yellow or drop unexpectedly, or until an infested plant is disturbed and small clouds of whiteflies emerge from it. Some whitefly species can cause greater damage by transmitting plant viruses.

Whiteflies (as well as soft scales, mealybugs, and aphids) excrete a sugary substance called honeydew, and an unsightly black fungus called sooty mold grows on the honeydew. Besides being unattractive, sooty mold may interfere with photosynthesis, reduce plant growth, and cause early leaf drop. Sooty mold usually weathers away after an insect infestation is controlled. Ants also feed on the honeydew, so if ants become a problem, plants should be examined closely for these sucking pests.

Biological Control

Citrus whitefly nymphs (Figure 3), one of the more common whitefly species attacking ornamental plants other than citrus, are highly parasitized by a small wasp, Prospaltella lahorensis. Citrus is the primary host of the cloudy winged whitefly, a species closely related to the citrus whitefly. Populations of citrus blackfly are also suppressed throughout the state by two tiny wasps. Certain predatory mites and lady beetles (lady bugs) also help suppress pest populations.

Figure 3. 

Citrus whitefly nymphs.


Credit: Lyle Buss, University of Florida
[Click thumbnail to enlarge.]

Carefully examine infested plants for evidence of parasitism. Parasitized whitefly nymphs will contain the larva or pupa of the parasitoid or an emergence hole may be visible on a nymph. The parasitoid does not attack the adult whitefly. If parasitism is evident, minimize the use of contact insecticides so the natural enemies have a chance to get better established.

Some whiteflies may also be naturally attacked by beneficial fungi (Paecilomyces) (Figure 4).

The silverleaf (sweet potato) whitefly replaced the citrus whitefly within the last 15–20 years as the most damaging whitefly species attacking ornamental plants. This whitefly is not strongly parasitized and is tough to control with insecticides. This species is not attacked by Prospaltella lahorensis. However, new invasive pests keep entering Florida and are currently causing considerable aesthetic damage.

Figure 4. 

Infected whiteflies.


Credit: Lyle Buss, University of Florida
[Click thumbnail to enlarge.]

Chemical Control

Insecticides that are labeled for whitefly control by homeowners are listed in Table 1, and professional products are listed in Table 2.

The first type of product to try is an insecticidal soap or horticultural oil spray. These products are safer for people, animals, and the environment, but they can still kill whitefly natural enemies. Be sure to read and understand the label instructions before doing any applications. If spraying, thorough coverage on the undersides of the leaves to the point of run-off is especially important. Repeat at weekly intervals as needed.

For synthetic insecticides, be very cautious of overusing the chemical class of neonicotinoids because of the possibility of developing pesticide resistance. Foliar applications tend to be with contact insecticides like pyrethroids. Foliar applications may provide quick control, but do not provide longterm control. Contact insecticides will also disrupt natural enemies and should be used selectively. Other application options include basal bark sprays, granular broadcast applications, tree injections, and soil drenches or injections. The active ingredient of a commonly used systemic insecticide is imidacloprid (ie., Merit, Marathon), but many other products are effective at reducing whitefly populations.

For More Information

  1. http://mrec.ifas.ufl.edu/lso/IAWG/FIG/The%20Fig%20Whitefly.htm

  2. http://miami-dade.ifas.ufl.edu/pdfs/urban_hort/Ficus%20whitefly%20flier%20updated%2008.pdf

Tables

Table 1. 

Insecticides labeled for non-commercial (homeowner) use against whiteflies in Florida.

Active Ingredient

Trade Name

Chemical Class

Bifenthrin

Ortho Bug-B-Gon Max Lawn & Garden Insect Killer

Pyrethroid

Cyfluthrin

Bayer Advanced Rose & Flower Insect Killer

Schultz Lawn & Garden Insect Killer

Pyrethroid

Imidacloprid

Bayer Advanced Lawn Complete Insect Killer

Bayer Advanced Tree & Shrub Insect Control

Neonicotinoid

Lambda-cyhalothrin

Spectracide Triazicide Once & Done Insect Killer

Pyrethroid

Malathion

Green Light Malathion

Ortho Malathion Plus Insect Spray

Organophosphate

Neem oil

Bonide Safer BioNeem

Green Light Neem

Green Light Rose Defense

Southern Ag Triple Action Neem Oil

Botanical

Paraffinic oil

Sun Spray Horticultural Oil

Biorational

Permethrin

Hi-Yield Indoor/Outdoor Broad Use Insecticide

Pyrethroid

Potassium salts

Safer's Insecticidal Soap

Biorational

Pyrethrins

Bonide Yard & Garden Insect Killer

Spectracide Rose & Flower Insect Spray

Botanical

Table 2. 

Insecticides suggested for professional use against whiteflies on Florida ornamentals.

Active Ingredient

Trade Name

Chemical Class

IRAC Class

Abamectin

Avid

Avermectins

6

Acetamiprid

TriStar

Neonicotinoid

4

Azadirachtin

Azatin XL, Azatrol

Botanical

26

Beauveria bassiana

Botanigard

Microbial

N/A

Bifenthrin

Bifenthrin Pro, Onyx, Talstar

Pyrethroid

3

Bifenthrin + clothianidin

Aloft

Pyrethroid + Neonicotinoid

3, 4

Bifenthrin + imidacloprid

Allectus

Pyrethroid + Neonicotinoid

3, 4

Buprofezin

Talus*

IGR

16

Clothianidin

Arena, Aloft

Neonicotinoid

4

Cyfluthrin + imidacloprid

Discus

Pyrethroid + Neonicotinoid

3, 4

Dinotefuran

Safari, Zylam

Neonicotinoid

4

Flonicamid

Aria*

Antifeedant

9C

Imidacloprid

Marathon*, Merit

Neonicotinoid

4

Paraffinic Oil

Horticultural Oil

Oil

N/A

Potassium Salts of Fatty Acids

Insecticidal Soap

Soap

N/A

Pymetrozine

Endeavor

Antifeedant

9B

Pyridaben

Sanmite

Acaricide

21

Pyriproxyfen

Distance

IGR

21

Spiromesifen

Forbid 4F, Judo*

IGR

23

Spirotetramat

Kontos*

IGR

23

Thiamethoxam

Flagship

Neonicotinoid

4

* For production nursery, greenhouse and/or interiorscape use only.

The inclusion of a trade name does not imply that the University of Florida endorses that particular product, nor does the omission of a product imply that other products do not work. Information included in these tables is obtained from insecticide trial reports, peer-reviewed publications, product labels, and the experience of subject matter experts.

Footnotes

1.

This document is ENY-317, one of a series of the Entomology and Nematology Department, UF/IFAS Extension. Original publication date October 1993. Revised March 2013. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

E. A. Buss, associate professor, Entomology and Nematology Department, UF/IFAS Extension, Gainesville, FL 32611.

The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication do not signify our approval to the exclusion of other products of suitable composition.


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.