How to get rid of little white flies on plants

Pests On Ornamentals And Vegetables: Whitefly Treatment In The Garden

In terms of garden pests, whiteflies are one of the most bothersome that a gardener can have in their garden. Whether they are on ornamentals or vegetables, whitefly control can be tricky and difficult. But controlling whiteflies in the garden is not impossible. Let’s take a look at the answer to the question, “How do you get rid of whiteflies?”

Identifying the Garden Pests Whiteflies

Whiteflies are part of a group of sap sucking insects that can cause problems in the garden. Other sap sucking insects include aphids, scale and mealybugs. The effects of these insects, including whiteflies, are nearly all the same.

The signs that you may have whiteflies or one of its cousins is a sticky film on the leaves, yellow leaves and stunted growth. The way to determine if you specifically have whiteflies is to inspect the insects you find on the plant. Typically, the insects can be found on the underside of the

leaves.

The garden pests whiteflies look just like their name. The will look like a tiny whitefly or moth. There will be several in one area.

Controlling Whiteflies in the Garden

Normally whiteflies become a problem when their natural predators, such as ladybugs, are not present in the area. This can happen for many reasons, ranging from pesticide use to bad weather.

Controlling whiteflies in the garden become difficult without the help from their natural predators; therefore, making sure that the area is good for their predators is important. Whitefly predators include:

  • Green Lacewings
  • Pirate Bugs
  • Whitefly Predators (actual name of insect)
  • Whitefly Parasites (actual name of insect)
  • Big-eyed Bugs
  • Ladybugs

Using these beneficial insects are the best way how to kill whiteflies.

You can also try spraying the affected plant with a lightly pressurized stream of water. This will knock the insects off the plant and will reduce, but not eliminate their numbers.

Also, for ornamentals and vegetables, whitefly problems and damage can be reduced if the plants are kept as healthy as possible, which means that you need to regularly feed and water the plants.

You can also try controlling whiteflies in the garden by using reflective surfaces, like foil or discarded CDs, around the plants. This can have a repelling effect on the whiteflies and may keep them off the plant. Alternately, you can try sticky tape, which will help to eliminate the current population of whiteflies on your plants and prevent them from laying more eggs.

Do not use insecticides as a way how to kill whiteflies. They are resistant to most insecticides and you will only make the problem worse by killing their natural enemies. That being said, Neem oil can be effective against these pests and is generally deemed safe for beneficials.

If you’ve noticed an epidemic of tiny white flying things on your tomato plants then it’s likely you’ve got an infestation of whitefly.

Whilst Whitefly may be a lessor concern than many other bugs out there, they can cause some damage in your vegetable patch, including spreading nasty diseases around. Whilst you may not see the affects of an epidemic right away, they are a sap sucking insect and can make your tomato plants to become weak and more susceptible to disease. Of all the vegetables in your garden, most commonly you’ll find your whitefly hovering around your tomato plants.

Whitefly epidemic on our tomato plant

Here are some ways you can get rid of your whitefly infestation:

Yellow Sticky fly paper

A spray free solution, you can pick this up from your local Bunnings but basically it’s a yellow sheet of sticky paper and the little flies stick to it. We’ve used this in the past with moderate success. However, we stopped using them when we caught a gecko and a few of our native bush bees stuck to the paper.

Organic Neem Oil

Used in organic farming, Neem oil is a natural oil from a seeds of a Neem tree which has a natural occurring pesticide. A great one for the organic gardeners tool belt. You won’t want to use this on any aquaponics systems as it can be moderately toxic to fish, but is generally safe for use around birds, mammals, bees and of course plants. Once sprayed on the plants it will only affect insects that eat the plant, so your native bees should be safe.

Lacewing Insects

I am yet to try this, but you can also purchase Lacewings to introduce to your garden. They are great bugs to have in your garden as they are not only predators to whitefly, but also a whole swing of other pests including aphids.

DIY White Fly Spray

What we predominantly use is a DIY spray using what we have lying around, it’s basically a DIY white oil. Whilst it won’t get rid of the full lifecycle of the whitefly it will keep them under control. Using a small spray bottle we fill it with water and add a tablespoon of vegetable oil, a tablespoon of dishwashing liquid, give it a good shake and spray on the flies. They basically can no longer fly so die. Don’t spray it on a hot day or you may deep fry your plants.

Do you have any home remedies for pests in your garden?

Pest Control: Whitefly and Aphids

Both aphids and whiteflies suck, literally. They are close relatives in the world of sucking pests, the aphid belonging to the superfamily of pests known as the Aphidoidea and whitefly to the Hemiptera, but both love to feed on the sap of your edible plants. Favoured plants are usually members of the gourd and nightshade families; meaning your pumpkins, cucumbers, squash and zucchini, along with tomatoes, eggplant, capsicum and chilli respectively.

Aphids

Optimal conditions: wet and warm (also known as spring)

Signature: clusters of small black or green dots on the stems of your plants and underside of the leaves. Turns the leaves yellow by sucking out their sap and then leaves behind a sugary residue – called honeydew – that ants feed on. An abundance of ants, that then protect the aphids, is a tell tale sign of a problem.

Aphids are semi-microscopic pests – seen with regular eyes or better with a microscope – that come as predictably as the change of season. Each spring as the weather warms up and rains fall in greater volumes, the aphid population rises faster than your pumpkin seedlings. In a blink of an eye, many hundreds of aphids take up cover and a feeding spot on your plants eating them from the inside out.

When eating, they create a sugary substance called honeydew, that then feeds their no.1 ally, the ant. If you happen to notice ants scampering up and down your plants, you can be sure that aphids are somewhere to be found.

Whiteflies

Optimal conditions: wet and warm (also known as spring)

Signature: brush against a plant and a million tiny white flies momentarily become airborne before returning to their sucking

Whiteflies behave in a similar fashion. The adults and their larvae simply love hanging out on the underside of leaves and suck sugary phloem juices all day. When disturbed they kind of flutter about a bit – performing an impromtu, but well organised Mexican wave – but soon want to be back in sucking position. Not only do they suck the life out of plants, they are also vectors for viruses which causes nasty plant diseases.

Adults live four to six weeks and lay over 100 eggs each (onto the underside of the leaf), so each plant can be quickly populated by an army of the white suckers. All in all, you want to make sure they don’t get too comfortable.

But remember that the whitefly and aphid are both seasonal pests that peak when conditions are ideal and then (usually) abate when the weather changes. This doesn’t mean you should sit back and do nothing, it just means not to freak out.

The worst thing you can do is begin spraying with chemical fixers which will discourage predators to come in and help. Rather ensure there is high diversity of different border-plants and flowers, particularly nasturtiums, which attract predators that become your secret helpers. This is not just some pseudo science stuff; professional growers constantly utilise this ‘free labor’ by strategically planting border plants to attract certain bugs. The ladybird is a huge ally.

Prevention: Keep the plants well spaced, allowing passage for airflow rather than the perfect, air-locked breeding ground. Consistently water, in the morning rather than the evening when all pests are more active. Don’t overfeed with nitrogen which tends to make plants more susceptible. Mulching the soil well will also help break the breeding cycle as this is where they lay their eggs.

Coping: they are attracted to the colour yellow like girls to diamonds, moss to stones, snot to a toddler’s nose. Hang yellow sticky traps around the concerned plants and they will fly onto them and get stuck. One sucker after another. Regularly clean the affected plants with a soapy spray to clean the leaves of both pests, the honeydew and the ants.

Eradicating: An organic white or eco-oil will help to eradicate the whitefly but alway make sure to spray the underside of all leaves. Nicotine sprays have also been found to work. The old hippy method is to soak ciggies in water overnight and then use the water in a spray bottle. But that’s pretty damn gross, so we prefer using eco-oil.

Whitefly

Though they look like tiny white flies or moths theses little sap suckers are a relative of aphids and mealy bugs. You know Whitefly has moved into your patch when you are greeted with a cloud of white each time you water or disturb your plants. Whitefly like company so if you have one you have hundreds or even thousands!

There are around 20 different species of Whitefly in Australia but the two most common species found in both home gardens are:

• the greenhouse whitefly (Trialeurodes vaporariorum)

• the silverleaf whitefly (Bemisia tabaci).

Both species look almost identical, but the silverleaf variety is a slightly smaller and a little more yellow in colour than the greenhouse whitefly.

Whitefly are sap sucking insects that attack a wide range of plants, including your veggie crops. And can these little sap suckers leave a trail of damage behind? Whitefly reproduce rapidly by laying eggs on the underside of leaves. Both the adult and nymph form of whitefly feed on leaf, bud and stem sap. Affected plant parts turn yellow and streaky. Leaves can curl and wilt which affects plant growth. Whitefly can also spread viruses from plant to plant as they feed.

Whitefly also excrete honeydew which can lead to infestations of sooty mould, a fungal disease that looks like black charcoal on the leaf. The saliva of the silverleaf whitefly contains a toxin that may cause further damage to the plant.

White fly are most prevalent in late spring and early summer but numbers will naturally decline in the cold of winter. However in warmer climates they are present throughout the year.

Controlling Whitefly

Whitefly are prolific breeders with a short lifecycle. Eradication of heavy infestations can be a challenge, but employing a combination of control methods to reduce numbers in the short term will lessen plant damage.

  • Yellow Sticky traps – Whitefly are attracted to the colour yellow so by hanging yellow sticky traps near your affected plants will help control their populations. You can purchase yellow traps from nurseries and garden suppliers or you can make your own at home using laminated yellow paper or plastic smeared with a sticky substance like Paraffin Oil or Vaseline. You need about one trap in every 3m x 3m area. Make sure you regularly disturb affected plants so the Whitefly swarm and fly into the traps. BUT BEWARE! These traps also attract beneficial insects so are NOT the method of choice!
  • Get the dust buster out and vacuum! Probably only effective at controlling small numbers and make sure you use low suction so your vac won’t damage the plant you’re trying to protect. Empty the dust bag contents into a labelled plastic bag and freeze before you discard to ensure the captured bugs don’t head back into the garden. Yes, its fiddly and slightly eccentric but may be worth experimenting with!
  • Hosing off and/or constant disturbance for 3 or more days in a row. Shake, rattle and hose those plants to annoy your unwanted guests. The idea is to cause enough disturbances to encourage whitefly to move on from your plants. Again probably only effective in controlling small numbers and unfortunately may not make you popular with your neighbours who are now hosting your whitefly problem!!
  • Attract natural predators such as Ladybirds, lacewings and hoverflies. These beneficial insects will all devour whitefly nymph and adult whitefly. Attract these beneficial insects to your garden by planting companion plants like marigolds and alyssum near your precious vegie crops. And don’t use chemical sprays that will also kill these good insects.
  • Home made or commercial organic natural sprays – Soap, botanical oils or even garlic and chilli sprays may deter Whitefly by adding another line of defence to your arsenal. However to be effective they need to come in contact with the insect which is difficult when they are airborne! However the nymphs are more vulnerable as they are on the undersides of leaves so this is where you need to direct your spray mist.

In enclosed greenhouse situations, infestations of whitefly can be controlled by using exclusion netting in doorways or by introducing the predatory wasps Encarsia formosa. They are available from a number of commercial suppliers.

Damage

Whiteflies produce a sticky substance known as honeydew, on which sooty mould can develop. Low numbers of whiteflies are not usually damaging and adults by themselves will not cause significant damage unless they are transmitting plant viruses. Virus symptoms include irregular ripening in tomatoes and blanching in carrots and broccoli.

When present in large numbers, whitefly feeding can affect plant growth causing distortion, discoloration, yellowing or silvering of leaves. Whiteflies can be a problem of fruit trees, ornamentals and vegetables. Some species of whitefly have a wide host range and the silverleaf whitefly (Bemisia tabaci) attacks more than 500 species.

Species in Western Australia

Five important species of whitefly occur in Western Australia. With the exception of the citrus whitefly and the native strain of Bemisia tabaci, which are native to Australia, all have been introduced. Species such as the greenhouse and silverleaf whitefly cause significant damage to commercial crops both here and overseas.

Identification of whiteflies is extremely difficult since most whitefly adults are white to off-white, 1.5–2.5mm in size and look like a small moth. The pupal stage has most of the characteristics used to identify whiteflies and is the only stage from which an accurate species identification can be made.

Life cycle and habits

All whiteflies have a similar life cycle, developing from the egg through four nymphal instars before becoming adults. Males and females are similar, except that the female is usually larger.

The female adult lays oval eggs in horseshoe or circular patterns on the undersides of leaves. Crawlers about 0.3mm long emerge from the eggs and wander over the leaf surface.

Within about one week the crawler settles and remains stationary for the second, third and fourth instars. At this stage the whitefly nymph (or larva) is flat and oval and resembles a small scale insect. Both legs and antennae are lost after the first moult, and subsequent nymphs remain fixed to the leaf surface. Nymphs may be yellowish or black in colour. Yellowish individuals are normally associated with herbaceous plants and black individuals are usually found on woody plants. The second and third instar nymphs are pale green and scalelike in appearance. Fourth instar nymphs feed initially, then feeding ceases before the adult begins to form internally.

The winged adult emerges from the fourth instar nymph which is often incorrectly called a pupa. When they first emerge from this stage, adult whiteflies are pale green or yellow, but they quickly secrete a white, waxy coating. All stages feed by sucking plant juices from leaves and excreting excess liquid as drops of honeydew as they feed.

Whitefly populations can develop very rapidly in warm weather and the greatest populations usually occur in spring and autumn. There are several generations of whitefly a year. The entire life cycle may be completed in as little as 18 days at temperatures of 28°C, depending on species. All growth stages can often be found on leaves at any one time.

Whiteflies – Vegetables

Back to leaf yellowing – seedlings and transplants


Adult whiteflies (Family Aleyrodidae) on leaf
Photo: Central Science Laboratory, Harpenden Archive, British Crown, Bugwood.org

Appearance

  • Eggs: Tiny, oval, suspended by short stalks on leaf underside, usually about 15 in a characteristic semi-circular pattern. Initially greenish-white, and then turning dark as mature.
  • Nymphs: Tiny, pale green to almost transparent, flattened oval-shaped discs which may or may not have a waxy white covering. There are 4 instars.
  • Pupae: Is the late 4th instar, which ceases feeding, is thicker and more opaque, and has long waxy filaments around the edge of body.
  • Adults: Resemble tiny white moths with powdery wings, about 1/10th inch in length, triangular in shape when viewed from above because the wings widen from head to tail.


Closeup of adult whitefly


Whitefly nymphs

Life Cycle/Habits

  • Whiteflies cannot overwinter outside in Maryland’s cold temperatures, but may successfully overwinter inside heated greenhouses.
  • They are generally reintroduced to the garden each year from infested greenhouse-grown transplants.
  • Eggs are typically laid on the newest leaves.
  • Newly hatched nymphs move to a desirable feeding spot, where they fasten on and begin feeding; the other 3 nymph stages are immobile.
  • Both nymphs and adults aggregate, feeding together on leaf undersides by piercing and sucking out cell contents.
  • Nymphs are inconspicuous and easily overlooked, but adults fly up in swarms when disturbed, and then quickly re-land.
  • Whiteflies excrete a sticky substance, known as honeydew.
  • There are several generations each summer.

Host Plants

  • Most common greenhouse vegetable hosts are cucumber, eggplant, and tomato.
  • In gardens, there are numerous hosts, most commonly bean, cucumber, eggplant, lettuce, okra, potato, tomato, squash, and sweet potato.


Whiteflies on underside of squash leaf

Signs/Symptoms

  • Piercing-sucking method of feeding produces stippling of leaves, followed by yellowing; drying and distortion, and premature leaf drop in heavy infestations.
  • Heavy feeding may wilt and stunt plants.
  • A black fungus called sooty mold grows on the honeydew excreted onto leaf and fruit surfaces. Sooty mold can be washed off produce, but interferes with leaf photosynthesis and weakens plants.

Whiteflies grooming
Video: Dr. Mike Raupp

Monitoring

  • Before purchase, tap transplants (especially tomato, eggplant and cucumber) and watch for whiteflies taking flight. In the garden, be alert for whitefly swarms, as well as sticky honeydew or the resultant sooty mold on leaves.

Prevention/control

  • Do not introduce infested transplants: inspect before purchasing by disturbing leaves and watching for whitefly flights.
  • Yellow sticky traps will catch some adults.
  • Whiteflies have many predators and parasitoids that suppress numbers as the season progresses. Early problems may clear up. Parasitized whiteflies look like pepper specks.
  • For heavy infestations, insecticidal soap can be sprayed on leaf undersides and repeated as necessary. Avoid spraying in very hot weather or on very stressed plants. Read label carefully.
  • Horticultural oils, neem, and insecticidal soap can be used for nymphs on leaves; pyrethrins are more effective against adults.
  • Control weeds because some may serve as alternative hosts.
  • Avoid continuous planting of favored crops to extend season/harvest, as it enables whiteflies to move from older to younger plants.

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