How to Kill Whiteflies on Plants, Get Rid Once and For All


While preparing my garden and growing my vegetables, I often notice some white mass on the plants and fluttering amongst the leaves of many of them. Upon further examination, I realised they are actually living insects. But just what are those little white flying bugs on your plants? They are called whiteflies; a menace in the garden. These tiny pale pests suck the sap from plants and spread disease.

How to kill whiteflies on plants? There are many applications a gardener can use to get rid of whiteflies. These include neem oil, SB Plant Invigorator and even Castile soap. However, to make sure to get rid of them for good, none of the methods will work on a one-off application. Applying regularly is the answer.

The best method(s) to use may also depend on the size of the garden, and the type of plants you may want to grow, as well as the location of the garden. In this post, I hope to open you to more options as to how to you may control and remove whiteflies, highlighting the benefits and possible hindrances to the use of some.

How do whiteflies damage plants?

Whiteflies are considered a major pest for crops, not only because they cause considerable damage and loss of production, but also because they feed on many different plants, causing damage to a wide array of plants.

Whiteflies can cause two types of damage to a plant:

  • Direct Damage
  • Indirect Damage

Direct Damage

direct damage and indirect damage. For direct damage, whiteflies can seriously injure plants by sucking the sap from the host plant, causing leaves to weaken, shrivel, and drop prematurely. Additionally, as they suck out the sap, they release toxic substances into the phloem, which then spread throughout the plant, causing metabolic imbalances in the plant which can in turn also cause discolouration on the parts of a leaf they have been feeding on.

Indirect Damage

In terms of indirect damage, whiteflies excrete molasses, or “honeydew,” a sweet substance that forms a sticky coating on leaves. The honeydew enables fungi such as sooty mould to form on the leaves, making them look dirty. Sooty mould may not necessarily be dangerous to plants, but when it exits in excessive quantity, it may damage plants indirectly by preventing sunlight from reaching leaf surfaces, essentially acting as a screen and reducing the photosynthetic capacity of the plant.

In severe cases of infestation, the damage caused by whiteflies can be devastating. Large numbers of whitefly can stunt plant growth, reduced fruit yield and premature death of plants. Preventing an infestation is therefore crucial if you are to protect your garden.

Whiteflies on underside of leaf

How to identify whiteflies

  • Possibly the easiest way to detect whiteflies would be to simply give the plants a soft shakeup. This is the first thing I do. It helps for easy and basic detection. A gentle rustle will make the whiteflies leave the plant for a brief moment, flying to the air, before falling back to the plant.
  • Whiteflies secrete a sticky substance known as honeydew. If you happen to notice these honeydew drops on the leaves of your plants then you should probably check for whiteflies/
  • You’re most likely to find Whiteflies feeding on the underside of leaves, so you should check the bottom of leaves for especially adults (which look like tiny, white moths).
  • If instead of adult whiteflies, you see white clusters on the undersides of the leaves, then these may be the eggs of whiteflies. So start taking all the steps to control whiteflies because these clusters are basically the eggs which will give birth to a swarm of these whiteflies.
  • Whitefly feeding also causes visible signs of damage. When attacked by whiteflies, then the plants start turning weak which can be a symptom to suspect whiteflies. They can give leaves a withered appearance and cause discolouration and yellowing, wilting and stunting of plants, premature leaf dropping and even death of the plant.

Plants normally affected by whiteflies

  • Tomatoes (Read my blog on tomatoes here)
  • Bell Peppers (Read my blog on peppers here)
  • Eggplants
  • Okra
  • Sweet Potatoes
  • Cabbage

Ways to get rid of whiteflies

  • Yellow sticky traps:  Available on Amazon. I found these helpful in trapping all sorts of plant damaging insects. They should be kept close to or around plants or within gardens affected by whiteflies. The whiteflies are attracted to yellow, making this trap effective are helpful for monitoring and suppressing adult populations. They are beneficial as they are easy to implement, require low maintenance, are inexpensive, and non-toxic. They may also disrupt the breeding cycle so fewer eggs are produced, as well as creating an effective monitoring method.
  • Hosing: one very simple method of getting rid of whiteflies is to physically remove them, by hosing them with a strong blast of water from a high-pressure hose. It’s best to make sure to get to the undersides of the plats, as this is where whiteflies usually stay. It’s also best to use the hose that works for high-pressure sprays, because while adult whiteflies are easily displaced, but the nymphs (tiny, scale-like creatures) are more difficult to remove as they cling tightly to leaves and will be able to hold on if the jet is not strong enough. This should be done regularly (at least once a week) for the best results and used together with other control methods. Among the benefits of this method, it is easy to do and inexpensive; however as far as negatives, this method may not remove all whitefly from plant, ad it must be repeated regularly for best results, which may make it time-consuming.
Whitefly Larvae
  • Natural predators: insects such as ladybug beetles, parasitic wasps, and predatory mites are all predators to whiteflies. They feed on whitefly eggs and whitefly parasite can destroy nymphs and pupae. A single female wasp can kill up to 95 whiteflies over her 12-day lifespan, making them a highly effective means of reducing whitefly numbers.
  • Among the benefits, it is a sustainable, natural, non-toxic means of biocontrol. The use of natural predators is easy to implement, it is also cost-effective, and is an effective way to kill large numbers of whitefly. The major disadvantage with this method is that if the natural predators are not released at an optimal level, it may lead to another infestation, with another set of issues.
  • Companion Planting: Flowering plants such as Mexican marigolds can be dangerous to these whiteflies. These flowers produce a scent that cannot be digested by the whiteflies and chasing them from the plants that they have infested.
  • Organic Neem Oil: Available on Amazon. Neem oil is an effective DIY method to control whitefly in the garden. It can be sprayed on plants to kill eggs, larvae and adults. By mixing about 1 oz/ gallon of water and spraying all leaf surfaces (including the undersides of leaves) until completely wet, this may prove effective against immature nymphs, stifling their development and killing them before they reach adulthood.
  • Also, it may act as a repellent, preventing adult whitefly from landing on plants or laying their eggs on the leaves. Because of the nature of this oil being natural, they are non-toxic Biodegradable and environmentally friendly. They can also e used on edible plants and house plants.
  • They are cost-effective and are easy to use. However, they only kill when applied directly, must be reapplied regularly, and are therefore time-consuming. Neem oil can be created by mixing: 1/2 tsp of organic neem oil concentrate

Making a Neem Oil Mix

  •  1/2 tsp of organic neem oil concentrate
  • 1 tsp of mild liquid soap
  • 1 litre of tepid water
  • SB Plant Invigorator: Available on Amazon. This product is totally organic and is used to boost plant immune systems. A side effect of this is that it is very good for killing whiteflies. It can be used around ponds without damaging the wildlife living within the pond. It will also help to remove aphids, powdery mildew and sooty mould.
  • Castile Soap Solution: Available on Amazon. Otherwise known as baby soap Castile soap is great for making a soap solution in order to help kill whiteflies. It does this by coating the whiteflies and knocking them off the plant to the floor.
  • They are unable to climb back on to the plant and suffocate on the floor. Castile soap is a pure soap and is not dishwashing detergent. This later product is a surfactant and can damage your plants and garden. Dishwashing detergents should not be used to spray on your plants.
  • Vacuuming: this may be an effective way to quickly remove whiteflies. You can use the high-pressure air coming out of the vacuum cleaner nozzles to simply blowflies away. Or alternatively, you can suck them.
  • Insecticides: these should be used as a last resort. I would not recommend insecticides for use against whiteflies, as many species are resistant to the chemicals. Chemicals can also have adverse effects on the environment.
  • They might not kill whiteflies, but they may affect other, more useful insects which may be useful in reducing their populations. A short-lived natural pesticide may, however, be useful by damaging the outer layer of soft-bodied insect pests, causing dehydration and death within hours.
aphid control – kill whiteflies – 5 ways including Neem Oil

Conclusion

Whiteflies are an especially pesky group of creatures. They might seem harmless individually, but that’s where the gardener gets caught out. These pests multiply very quickly and before you know it you have an infestation on your hands. You want to do all you can to remove them from your plants and out of your garden, but like with most things, it requires some effort.

These options I have laid out can provide the most effective of results. I believe that in order to more effectively control whiteflies, a combination of these options will provide the best possible outcome. Mixing these options will enable you to see a reduction of the pests in your garden.

Each garden is different and has its own set of growing conditions. Some of this may make it easier for this pest species to multiply. It may be worth looking at your husbandry or even the way you water which may all help in tackling this pest.

I trust you found this post helpful and are ready to get those bugs off your plants. Subscribe to the blog for more helpful posts like this.

Remember folks; You Reap What You Sow!

Tony O'Neill

I am Tony O'Neill, A full-time firefighter and long term gardener. I have spent most of my life gardening. From the age of 7 until the present day at 45. My goal is to use my love and knowledge of gardening to support you and to simplify the gardening process so you are more productive

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