How To Kill The Whitefly: Identify, Treat And Prevent

Whiteflies are tiny, flying insects that can be found around houseplants and on the leaves of plants. Your plant may look a little more lackluster than before or have sticky substances all over its leaves with no apparent cause. You should watch out for these signs because you might have yourself an infestation problem yourself! But don’t worry, we’re here to help identify your whitefly issue easily, plus give solutions, so it doesn’t happen again in the future!

You’ll find more information about this topic below, but we’re only covering it in the section How to Kill the Whitefly.

Identifying Whiteflies

whiteflies opposite and an egg on the leaf

The Silver leaf whitefly is one of the most common species found in southeastern states, and their yellow coloration makes them hard to miss. The average length ranges from 1/10th to 1/16th inch long. All the different types attack many plants, but after sucking out their juices, they leave behind something called honeydew which coats leaves and other surfaces around them – making everything sticky!

Whitefly Control

Whitefly control is essential because those insects cause diseases in plants. The feeding of whiteflies makes the plants weak and causes them to lose the capability to photosynthesis properly. The leaves may first wilt, turn yellow or pale, and slow the growth of the plant. If honeydew is present, they have been feeding for at least a few days.

There is often a colony of ants in the area because they enjoy eating honeydew, which is excreted by whiteflies. Look for tiny white insects on the leaves and the plants’ surface. It is easy to see if there’s an infestation if they are present because these critters often buzz around in a swarm when disturbed.

The Greenhouse Species Of Whiteflies

The presence of eggs indicates a whitefly hatching. When a new generation of larvae emerges, they are legless ovals that suck the juice out of plants and remain until their next offspring come to life.

The whiteflies that frequently invade greenhouses are most prevalent in California. Whiteflies can be found on indoor plants, in greenhouses, and anywhere outside where gardening is taking place.

The Nymphs

Whiteflies are like many insects because they have nymphs that go through an immature stage and eggs laid by the adults anywhere. Whiteflies make their homes under leaves where the adults lay eggs in arcs or circular patterns. The nymphs of the whitefly are small, have no legs or wings, and have oval bodies. The adults’ appearance is similar to a moth with wings.

The Giant Whitefly

The giant whitefly is also known as the Mexican Whitefly. Whitefly species have infested ornamental plants and hibiscus in California. The first sightings of this insect were seen in 1992 when it was found near San Diego before spreading to southern areas such as Louisiana, Florida, Texas, and some parts of Arizona. Its name derives from its much larger size than any other member of this family – making it one large problem for your home garden or business landscape!

Best Way To Identify Whitefly

To identify this species of whitefly, look for the waxy deposits that adults leave on leaves. These are usually found on the surface of both the upper and lower leaves of the plant. Whiteflies lay their eggs into the wax secretion of plants, whose long filaments resemble human hair and are about two inches in length.

The Affected Leaves

The leaves become bearded-looking due to the filaments. Giant whiteflies are attracted to certain avocados, mulberry, hibiscus, banana, citrus, and giant birds of paradise. It’s important to regularly inspect any plants in your garden for an early whitefly infestation. Trifecta can be used as a preventative to reduce the likelihood of that happening.

Whitefly Life Cycle

nymph eggs and adults of whiteflies on a leaf

Although the life cycle of whitefly varies depending on temperature, in general, it can take anywhere from one month to develop from egg to adult. The life cycle of whiteflies consists of four different stages, the pupal stage, and adulthood. The lifespan for adults is about one to two months.

The females lay whitefly eggs on the underside of leaves near their top. The eggs hatch, and then nymphs move a short distance before remaining stationary and feeding.

During the second to fourth stages, whiteflies show no signs of movement. Towards the end of the last stage, red eyes develop as they approach adulthood. When they become adults, a hole shaped like a T can be seen on plants eaten by these pests.

What Are The Most Common Reasons For Whitefly Infestation?

Drought

Plants stressed from water deficiency, such as plants with some foliar yellowing or necrosis indicating low leaf water potential, are likely to be more susceptible to whitefly infestations. If you often forget to water your plants when they need it, such as during summer months or if you live in an area where the heat encourages drought-like conditions, there’s a good chance that plants have been dehydrated.

When there is drought stress, pests such as whiteflies are more likely to come about. One (or both) of the factors that cause this is a higher rate of reproduction and development time.

Moreover, dry conditions often favor insects with piercing, sucking mouthparts (like whiteflies), so they tend to flourish during periods of drought. Drought can also negatively impact the survival and development of ladybugs.

Ladybugs are predators of whiteflies, a common pest in horticulture. Fewer ladybugs during dry summer months can spell out bad news for your plants.

Overuse Of Insecticides

While insecticides may seem like the best way to get rid of your whitefly problem, these can often be harmful to those who come in contact with them. Many insecticides are not specific and will harm any insect, including ladybugs or bees. Drenching your garden with a lot of insecticides will wipe out every pest around, including beneficial predatory species.

Many predators exist that feed on whiteflies, such as spiders, ladybug beetles, and parasitic wasps. However, these creatures may be killed off during insecticide treatment when insecticides are used as a defense against whiteflies. This leaves the whiteflies to resurface in full force.

What’s more, using insecticides can also harm pollinators and other essential garden creatures that help with gardening processes.

Use Of Nitrogen Fertilizer

Nitrogen-rich fertilizers work wonders for plants, providing some of the nourishment they need to flourish. As a result, you may not think twice about using them in your flowerbeds – it’s good for plants! However, that also means nitrogen-rich fertilizers can promote whiteflies to attack and feast on your plant too.

Studies have shown that excessive reliance on nitrogen fertilizers can lead to a greater nitrogen concentration in plant tissues. This may be the reason for your high re-infestation rate, so consider limiting your use of these fertilizers or changing to lower rates altogether.

Enemies Everywhere

Ladybugs are a natural enemy of the whitefly and can be helpful for those trying to keep an infestation under control. Unfortunately, even ladybugs may fall prey to other species that want to eat them.

If you have some birds like swifts and swallows, certain types of spiders, or other predators in your garden that eat ladybugs, they may be responsible for recurrent whitefly problems.

How To Prevent Whiteflies

sight of a flock of whiteflies invading the leaves of a plant in the garden

Be sure to explore prevention methods that don’t use insecticides If your plants are under constant attack from whiteflies. This can help keep them out of your garden and houseplants without the use of potentially harmful chemicals.

Frequent Inspection

Striking down any whitefly presence before it has the chance to spread is imperative. If you don’t take care of a small population right away, they can quickly bring themselves into a large problem that will be difficult to manage.

Visually inspect the undersides of leaves for signs of whiteflies, eggs, or excrement to catch them before they have a chance to grow! Blast the leaves on your plants with a high-pressure hose if necessary. This removes whitefly quickly and can help to reduce infestations of these flies in your garden space.

Yellow Sticky Traps

Whiteflies are drawn to the color yellow to help get rid of them using a sticky trap packed with strips or packets of yellow paper.

Releasing a homemade trap of yellow index cards and petroleum jelly will eventually attract the whiteflies due to their attraction to bright colors and kill them by sticking them down.

Keep in mind that even though you clear away the whiteflies, some eggs might stay on the underside of leaves. Make sure to use one of the other methods listed here in addition to the sticky traps, or they’ll keep coming back.

Once you take care of the whiteflies, it may be useful to keep new traps installed in a preventative measure. There are many different types of sticky traps–find the ones that work best for you.

Reflective Mulch

You can keep whiteflies off your plants by using reflective, plastic mulch. To help fend off and control whiteflies, reflective mulches should be spread around vulnerable plants to confuse them and reduce their populations. Using these methods can stop them from landing on your plants and help to ensure that an infestation does not take hold.

Natural Predators

Some bugs, such as ladybugs, kill whiteflies. In order to control and reduce the numbers of these pests, it is possible to buy a large number of natural predators. A small wasp called Encarsia Formosa is an extremely effective natural enemy of whiteflies, and it’s much less scary than its name suggests!

The Biological Ways To Kill Whiteflies section below contains some examples.

Neem Oil

As we discussed, insecticides may not be the best way to deal with insects like whiteflies due to their negative effects on beneficial insect species. Luckily some natural alternatives don’t harm the environment. Neem oil is one such alternative and has been shown to work just as well as pesticides without any unwanted side effects.

This natural plant extract can be sprayed on leaves that effectively kills whiteflies on plants but is low in toxicity for pollinators, spiders, and ladybugs. Use this spray weekly to ward off whiteflies and prevent them from taking up residence.

Use A Natural Repellant

An easy way to repel whiteflies is to bring a plant with natural repellant capabilities near your plants. Various plants like mints, parsley, cilantro, onion, or any other aromatic plant can drive whiteflies away; alternatively, nasturtiums, zinnias, pineapple sage, and hummingbird brush will act as a deterrent. If used in conjunction with a good hose-down and soap spray, it can help keep whiteflies away after killing eggs and larvae.

The Treatment And How To Kill Whiteflies

the appearance of whiteflies filled with white cotton and eggs around it

For the best chance of success killing your whiteflies, check them out in the early hours of morning or evening when they’ll be at their most sluggish.

You may need to combine multiple of the below methods to make sure you kill them, as whiteflies can be persistent. Repeating treatments could be necessary until they are gone for good.

Hose It Off

Bring your plant outside and spray it off to remove any adults or eggs. Do this while paying attention to the underside of leaves as well as new growths. Please keep it away from other plants, so insects don’t start over again with a different plant, too.

Use A Vacuum

Carefully use a vacuum attachment on your handheld vacuum cleaner in low suction setting to vacuum the underside of leaves every few days, collecting eggs, larvae, and adults alike. Attach your vacuum to the outside of your house and empty it in a large dumpster. Beware, single female whitefly can produce over 400 eggs, so be thorough and avoid damaging your plant.

Insecticidal Sprays (DIY And Otherwise)

To kill whiteflies, coat the undersides of your plant’s leaves with Neem oil or a soap spray. In order to get the best results, use this product in the morning or evening when it’s cooler. Avoid spraying the top surfaces of your plant leaves to avoid blocking photosynthesis (the whiteflies are not found there). Here are a few options to try:

To make your own remedy, try adding 8 drops of dish soap and 1 liter of warm water to a spray bottle. This can then be applied to any leaf in the garden.

Test the mixture on an out-of-the-way leaf to make sure it doesn’t damage your plant leaves. The best way is to saturate a leaf with it 2 days later, and if you notice any burns, reduce the mixture by adding more water or less soap.

Spraying the underside of each leaf with soap spray and repeating every other day should get rid of the infestation. This process may take a few weeks to remedy the pest.

A simple mixture of equal parts vinegar and water can also be used; make sure to test this on a single leaf first, then dilute the mixture accordingly. Apply the solution as needed.

Natural Essential Oil

Neem oil is both an effective treatment for pests of all types and a great preventative measure. It can also last for days due to its nice scent.

To help prevent whiteflies from bothering your plants, you can mix 1 tablespoon dish soap and a teaspoon of Neem oil in a gallon of water. Using an outdoor sprayer, apply the mixture to the underside of leaves every 3-4 days for four months from planting time.

Tests done on a leaf first are necessary so there is no damage to the leaves themselves. The oil should remain on the plant until the whiteflies are gone, and occasionally it is necessary to rinse off dead bugs. Use Neem oil every so often as a preventative measure to defend against future infestations

Note: Do not use neem oil on plants in direct sunlight – it can trap heat and dehydrate the plant.

Prune And Treat

You can also control a smaller whitefly population by keeping your leaves trimmed. Trim infested leaves and dunk them in a bowl of rubbing alcohol or dish soap. You’ll have to use sticky traps again for effectiveness, but watch out for the chance that eggs will be laid by these troublesome insects. Early identification of the problem is key to effective treatment.

Biological Ways To Kill Whiteflies

side view of a whiteflies on a green leaf

Biological control methods effectively suppress whitefly populations in greenhouses in Europa, but they are not widely used in the United States. The following biological control agents for whitefly are available:

Encarsia Formosa

Encarsia Formosa is a parasitoid that lays its eggs in whitefly nymphs. These insects are even smaller than the whiteflies they attack. The parasitoid larva grows inside the whitefly nymph until it captures its host, at which point it will consume the insect from within. This parasitoid will attack three common pests but is best at tackling the greenhouse whitefly in cooler climates. The commercially available strains of this parasitoid do not provide good control of sweet potato whitefly.

Eretmocerus eremicus

Eretmocerus eremicus is another parasitoid commercially available and generally provides better control at higher temperatures than Encarsia inaron.

Delphastus Catalinae

Delphastus catalinae, a tiny predatory beetle (1/15 inch) that consumes whitefly eggs and nymphs, prefers to attack all whitefly species but has a sweet potato whitefly preference. It will avoid eating whitefly nymphs with parasitoids developing within them, meaning that it can be released with a parasitoid without interfering with the parasitism.

Biological control is usually more expensive than chemical control and often does not result in the complete elimination of the pest. However, if you have a history of whitefly infestations that do not respond well to chemical controls and you are operating an organic farm, biological control may be able to accomplish what chemicals cannot. Moreover, organic biological control can add value to your crop. If you are considering biological control, find an expert who specializes in using these organisms to help you make your best choice.

FAQs

Where Do Whiteflies Live?

These insects, which thrive in tropical and subtropical regions, have become a major concern for the agricultural industry. Economic losses from whitefly infestations are estimated to be in the millions of dollars.

What Do Whiteflies Eat?

The whitefly’s diet consists mainly of the liquids it extracts from plants. All stages are usually found on the underside of plant leaves.

What Do Whiteflies Look Like?

Whiteflies might be thought of as a type of fly, but they actually belong to the order Hemiptera, a family within true bugs.

Whitefly is an insect with two pairs of powdery wings.

How Did I Get Whiteflies?

Homeowners sometimes encounter whiteflies by bringing them inside with infested greenhouse plants or products because they hide and feed on the undersides of leaves. Households with certain ornamentals such as hibiscus plants and mulberry trees are particularly prone to encountering whiteflies.

How Serious Are Whiteflies?

Whiteflies can be fatal to some plant life. The foliage that they DON’T kill may suffer faded coloring and stunted growth, leaving the plant unsightly and making it less likely to survive. Whiteflies also excrete honeydew, which attracts other insects such as ants. One way to prevent a plant from being severely damaged is to quarantine it and inspect it for the presence of pests.

The Bottom Line

Repeated whitefly infestations are a hassle. These tiny pests can damage greenhouses and gardens when left unchecked, and it’s not always easy to find an effective way to stop them.

Unfortunately, there is no end to the number of whiteflies you can have to deal with when they fly into your yard. Identifying the source of your whitefly infestation can help you solve the problem.

There are many different reasons why you might be experiencing a whitefly infestation. You can take the necessary steps to ensure that they’re eliminated efficiently and quickly, including choosing the right fertilizer, eliminating pesticides, or setting up traps around your property.

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