Eretmocerus eremicus
Whitefly parasitoid (Eretmocerus)- Rate
- 1–10 /m² per release, weekly
- Temp
- 77–84 °F (25–29 °C) best; needs a 68 °F (20 °C) daily average
- Best for
- Greenhouse parasitoid of choice; warm crops
Pest
Silverleaf whitefly
Bemisia tabaci
The short answer
In the US this whitefly is usually called silverleaf or sweetpotato whitefly. The pest form is Bemisia tabaci MEAM1, formerly the "B biotype". It looks like greenhouse whitefly but is smaller and yellower, and it holds its wings tent-like. It is a pest of hot regions and warm greenhouses, and it does more than make leaves sticky. It transmits tomato yellow leaf curl virus and other viruses, and its nymphs cause irregular ripening in tomato and silverleaf in squash. Parasitoids, predatory mites and reflective mulch reduce numbers. Sprays struggle, because it lives under the leaves and resists many insecticides.
hero macro · adults with tent-like wings on a leaf underside
Adult Bemisia tabaci and yellowish nymphs on a leaf underside. Photo: pending.
Identification
Adults are smaller than greenhouse whitefly, which UMass puts at 1/16 in (1.6 mm); UF/IFAS measures the female body at 0.96 mm and the male at 0.82 mm. The body is light yellow and the wings white. At rest the wings are held close to the body and tilted like a roof, with a small gap along the back. Greenhouse whitefly holds its wings flatter, meeting in the middle, and UF/IFAS notes that greenhouse infestations are occasionally a mix of the two.
Eggs are laid on leaf undersides, often in a semicircle around the female's feeding site; they are white at first and turn amber-brown. The scale-like nymphs are greenish-yellow, flat and oval. The final red-eyed nymph is the best stage to identify. It is soft and whitish-yellow, its sides slope down to the leaf, and it has few or no long wax filaments, unlike the upright, fringed pupa of greenhouse whitefly.
Bemisia tabaci is a complex of look-alike species that can only be told apart genetically. MEAM1 — formerly the B biotype, and once named Bemisia argentifolii — is established throughout the US. MED, the former Q biotype, has been found in 27 states, mostly in greenhouses, and is even less susceptible to insecticides.
Easily confused with
- Greenhouse whiteflyAlso a pestSilverleaf whitefly is smaller and yellower, with wings tilted roof-like and a gap between them. Its pupae have sloping sides and few or no long wax filaments.
- Parasitised whitefly pupaeBeneficial — leave itSilverleaf whitefly pupae parasitised by Eretmocerus turn light brown. Leave them: the wasp is developing inside.
- Bandedwinged whiteflyAlso a pestBandedwinged whitefly has brownish bands across its wings, and its nymphs have only short wax filaments.
Damage symptoms
The direct damage is the same as any whitefly's: sap loss, honeydew and sooty mould. This species is serious because of what it does beyond that. Feeding by the nymphs, not the adults, triggers plant disorders, and in Florida irregular ripening cost tomato growers an estimated $25 million in 1989 (UF/IFAS). The adults transmit viruses, including tomato yellow leaf curl virus and several cucurbit viruses. UC IPM calls the spread of tomato yellow leaf curl a major threat to tomato production.
- Tomato fruit that ripens unevenly, with pale streaks outside and hard, white, unripe tissue inside
- New leaves on squash and pumpkin turning silvery, but not the older leaves the nymphs are feeding on
- Tomato and bean plants infected with whitefly-borne viruses such as tomato yellow leaf curl
- Sticky honeydew and black sooty mould on leaves and fruit
- Pepper streak, pale stems on brassicas, and yellowing of new growth on many hosts
Lifecycle & degree days
In warm weather a generation takes about three weeks. At 77 °F (25 °C) eggs hatch in 6–7 days and the nymphal stages take roughly two weeks more (UF/IFAS). It overwinters outdoors as far north as South Carolina and survives further north only in greenhouses. Adults that develop on ageing plants can migrate several kilometres, so whiteflies pour into new plantings when a nearby crop is harvested or dries up. In California cucurbits, UC IPM reports that populations peak in late summer and fall away by November.
- Egg hatch
- 6–7 days at 77 °F (25 °C)
- Egg to adult
- About 17–22 days (our sum of UF/IFAS stage times; eggs timed at 77 °F)
- Eggs per female
- 66–300, over a 10–24 day life
- Host range
- 500+ species in 74 plant families
- Overwinters
- Outdoors north to South Carolina; greenhouses beyond
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Host crops
TomatoPepperCucumberSquash & pumpkinMelon & watermelonBeansCabbage & other brassicasEggplantHibiscusChrysanthemum & poinsettia
UF/IFAS counts more than 500 host species in 74 families. In Florida it is a major pest of tomato, pepper, squash, cucumber, beans, eggplant, watermelon and cabbage, and of potato, peanut, soybean and cotton. Poinsettia, hibiscus and chrysanthemum are among its ornamental hosts. UC IPM adds crape myrtle, lantana and roses. Smooth-leaved varieties and glossy brassicas are less favoured for egg-laying than hairy or waxy ones.
Monitoring & action thresholds
Action threshold
4 adults per leaf
UC IPM's figure for California tomatoes: about 4 adults per leaf in a random 30-leaf sample. For Florida tomatoes, UF/IFAS times sprays against nymphs at 5 nymphs per 10 leaflets to prevent irregular ripening. On melons, UC IPM advises treating before numbers pass 2 adults per leaf. Where a virus is the concern, no threshold is low enough, and prevention matters more: clean transplants, reflective mulch and host-free periods. There is no published home-garden threshold.
Check field and garden edges first, because they are colonised first. UC IPM advises checking twice a week when a nearby host crop is being harvested or drying up. Yellow sticky traps show when adults first arrive. On melons, UC recommends checking the terminal leaf on 50 plants within two hours of sunrise and counting leaves with at least one adult. If half the leaves have one, there are at least 2–3 adults per leaf. For nymphs, count the flat, egg-shaped scales in a 1 cm² disc of leaf (UC uses a quarter to mark it).
Beneficial
Biological control
In unsprayed Florida fields, natural enemies usually keep this whitefly below damaging levels (UF/IFAS). The main ones are Encarsia and Eretmocerus parasitoids, plus predators such as lacewing larvae, minute pirate bugs and big-eyed bugs. California is different: the whitefly arrived without its own enemies, and UC IPM says the native ones attack it without holding it below damaging numbers. In greenhouses, UF names Eretmocerus eremicus, the Swirski mite and the beetle Delphastus catalinae as commercial controls. UMass recommends Eretmocerus over Encarsia formosa for this species, and UConn reports that Eretmocerus with the Swirski mite suppressed whitefly on poinsettia better than either alone. None of these stops incoming adults from spreading virus.
Amblyseius swirskii
Swirski mite- Rate
- 25–100 /m² per release; 100–300 /m² on hot spots
- Temp
- 20–32 °C best; not effective below 18 °C (Biobest: 15 °C)
- Best for
- Eggs and young nymphs in cucumber and pepper
Delphastus catalinae
Whitefly ladybird- Rate
- 10 per infested plant or 100 per hot spot, weekly for 3–4 weeks
- Temp
- 72–80 °F (22–27 °C) best; suppliers quote working ranges as wide as 61–95 °F (16–35 °C); does not fly below 55 °F (13 °C)
- Best for
- Heavy patches, alongside parasitoids
Geocoris spp.
Big-eyed bugs- Kind
- Wild — attract it
- Best for
- Wild predator in the field and garden
Cultural controls
Cultural control is the main defence against the viruses, because it keeps adults off young plants.
- Use clean transplants — infested transplants are how this whitefly was carried into new parts of California
- Lay silver reflective mulch before planting: UC IPM reports it delays build-up on tomato by 4–6 weeks, until leaves cover about 60 % of it
- Leave the longest possible gap between host crops, and plant half a mile upwind of melons, cole crops and cotton where you can
- Destroy crop residues and weeds as soon as a crop is finished
- Pull up and dispose of tomato plants with leaf curl virus so they cannot infect healthy ones
- In greenhouses, fine insect mesh on vents and UV-absorbing plastic reduce whitefly entry (UF/IFAS)
- In hot regions, cover young cucurbits with row covers and remove them gradually at bloom
Chemical, last resort
Resistant to many insecticides, and MED more so — hit young nymphs early and cover the leaf undersides. Imidacloprid and bifenthrin are in UC IPM's most bee-toxic class; never apply them to flowering plantsCheck any product before it goes on. Open the compatibility matrix →
- Insecticidal soapREI 12 h
- Narrow-range oilREI 4 h
- SpirotetramatREI 24 h
- PyriproxyfenREI 12 h
- Imidacloprid (soil-applied)REI 12 h
- BifenthrinREI 12 h
Rating: the effect on this pest's natural enemies if a spray hits them or they feed on treated plants. REI is the re-entry interval on farm and greenhouse labels; home labels usually give none, so follow the label.
Sources
UF/IFAS EENY-129, Sweetpotato Whitefly B Biotype, Bemisia tabaci (McAuslane & Smith, rev. 2015)
UF/IFAS ENY-705, A Threshold for Timing Insecticides against Silverleaf Whitefly on Tomato (rev. 2016)
Krause-Sakate et al., First detection of Bemisia tabaci MED in Oklahoma, J. Econ. Entomol. 2025
UC IPM Pest Management Guidelines: Tomato — Whiteflies (text updated 2013)
UC IPM Pest Management Guidelines: Cucurbits — Whiteflies (treatment table updated 2024)
UC IPM Pest Notes 7401, Whiteflies (M.L. Flint, updated 2015)
UC IPM, Relative Toxicities of Insecticides and Miticides Used in Tomatoes to Natural Enemies (2016)
UMass Extension, Whiteflies on Greenhouse Crops (T. Smith, 2012)
UConn Extension IPM, Biological Control of Whiteflies
Page status
Drafted from the sources below, then checked claim by claim against those sources on 23 September 2026.
Suggest a correction →Silverleaf whitefly by crop
The same pest behaves differently on different hosts. Each page below gives the host-specific control, rate and threshold.