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GREENHOUSE WHITEFLY

Steven Frank & James R. Baker, Extension Entomologist Emeritus

CAUTION: This information was developed for North Carolina and may not apply to other areas.

General Information

GREENHOUSE WHITEFLY, Trialeurodes vaporariorum (Westwood), Aleurodidae, HOMOPTERA

The greenhouse whitefly is a tiny (1/16 inch long insect that resembles a tiny moth). The almost microscopic, oblong, pale green to purple eggs are inserted into the lower leaf surface, often in a circle or crescent. The tiny nymph, yellow with red eyes, becomes a flat scale-like insect appressed to the lower leaf surface that grows to about 1/32 inch long.

Biology

Greenhouse whiteflies are worldwide pests of greenhouse-grown ornamentals and vegetables. First discovered in England in 1856, they were found in the United States in 1870. Tropical Central or South America are suggested origins of the greenhouse whitefly. Greenhouse whiteflies infest a wide variety of ornamental and vegetable crops, and they can survive outdoors during the growing season, particularly in sheltered locations. Even trees may be infested (redbud, Kentucky coffee berry, and avocado). Infested plants become chlorotic and unthrifty. Secondary infections of honeydew and sooty mold further detract from the appearance of the crop. Unless controlled, greenhouse whiteflies may completely destroy the commercial value of a floricultural crop. Greenhouse whiteflies reproduce slowly (a generation every 30 to 45 days), but each female may lay up to 400 eggs and live as long as 2 months. Adults are usually found on the lower surface of new

whitefly adult

leaves. Here they insert their eggs that hatch 5 to 7 days later. The new crawlers move about the plant for a day or two, often from leaf to leaf before inserting their mouthparts to feed. Once this occurs, they probably do not move again until mature. The crawlers molt into nymphs and then pupae. Finally, a new generation of whitish-yellow adults emerges. They are soon covered by a white, waxy bloom.

Control

It was previously thought that lower greenhouse temperatures used in the culture of some bedding and potted plant varieties tended to encourage infestations because naturally occurring parasitic wasps (Encarsia formosa) are reproductively inhibited at temperatures below 75F. This does not seem to be the case. The Encarsia formosa, now in the commercial biological control trade, seems to works well at most greenhouse temperatures. Chemical control of whiteflies is difficult because the eggs and immature forms are resistant to many aerosol and insecticide sprays. One must make regular applications of pesticides to control emerging adults until the last of a whole generation of immature whiteflies has emerged.

Table 1. G= greenhouse, L= landscape, N= nusery, I= interiorscape. *Suitable for homeowner use.

Active ingredient

Trade name

Labeled location

Signal word

IRAC
MOA
group

Compatible with
beneficials

abamectin

Avid

G, L, N

Caution

6

Yes

acephate

Orthene, *Orthenex

G, N, L

Caution

1B

No

acetamiprid

TriStar

G, N, L

Caution

4A

Yes

bifenthrin

Talstar

G, N, L, I

Caution

3

No

buprofezin

Talus

G, N

Caution

16

Yes

dinotefuran

Safari

G, N, L, I

Caution

4A

Yes

flonicamid

Aria

G, N, L

Caution

9B

Yes

horticultural oil

*many

G, N, L, I

Warning

-

Yes

imidacloprid

Marathon II

G, N, I

Caution

4A

Yes

imidacloprid

*Merit

N,L, I

Caution

4A

Yes

insecticidal soap

*many

G, N, L, I

Warning

-

Yes

kinoprene

Enstar II

G

Caution

7A

Yes

novaluron

Pedestal

G, N

Caution

5

Yes

pyridaben

Sanmite

G,L,N

Caution

21A

Yes

pyriproxyfen

Distance

G, N, L

Caution

7C

Yes

spirotetramat

Kontos

G,N

Caution

23

Yes

thiamethoxam

Flagship

G, N

Caution

4A

Yes

 

Recommendations for the use of chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by the North Carolina Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage and examine a current product label before applying any chemical. For assistance, contact an agent of the North Carolina Cooperative Extension Service in your county.

Other Resources

© 2001 NC Cooperative Extension Service

Prepared by: James R. Baker, Extension Entomologist

ENT/ort-10
May 2000 (Revised)
Web page last reviewed January, 2011 by the webperson.