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Are Whiteflies Harmful To Humans – Important Information!

Whiteflies are winged insects with soft bodies that are closely related to mealy bugs and aphids. Despite their name, they are not a flying species, although they have wings and can fly.

They can grow to 1/12 inch with slightly triangular shapes and usually appear in groups under the leaves. They’re typically active during the daytime and scatter when disturbed, making them easier to detect than some nocturnal pests and insects.

There are many whitefly species, but most of them affect a small number of the host plants. The question you need to ask yourself is are whiteflies harmful to humans.

However, some of their species affect a wider species of plants, making it a problem in horticulture. The whitefly species comprise of banded winged whitefly, greenhouse whitefly, Silverleaf whitefly, and giant whitefly, and many more.

Silverleaf whiteflies are more yellow and slightly smaller than other whiteflies and are commonly found in the southern parts of the U.S.

Are Whiteflies Harmful To Humans
Cabbage Whitefly via Wikimedia

What Is The Lifecycle of The Whiteflies?

Whiteflies start their life in the form of an egg. The female ones lay their eggs under the leaf. Eggs are yellowish-white and pointed on both ends.

They all would hatch to male whiteflies if they did not mate with the males when laying eggs. Females mate with their offspring to lay female eggs. One female will lay about 400 eggs and lay them in a circle.

When they mature, the eggs slowly darken and hatch, producing a nymph called a crawler. Young whiteflies are mostly oval and flat in shape.

This nymph goes through four stages as it slowly grows into adulthood but has only functional legs at this early stage. The crawlers make their way through the leaves before attaching their mouth to the surface of the leaf and starting to leaf.

When they change in the following stages, they remain closely attached to the plant by mouth. In the last stage, the nymph will develop into a pupa and transform into an adult.

Typically, this pupa is spikey and oval. After the whitefly changes, it comes out of the pupa stage, and the wings start to unfurl and then dry. The entire cycle can then be restarted. The adult lives for several months and feeds on the sap-like nymphs.

How to Recognize Whiteflies

Whiteflies use their pointing mouths to suck plant juice and then produce the sticky substance called honeydew. Honeydew can cause fungal diseases, like the formation of sooty mold on the leaves. With a heavy feeding of the whiteflies, plants will become weak quickly and may not photosynthesize.

The leaves will turn yellow or pale, wilt, growth slows down, and eventually, the leaves wither and fall off the plant. Typically, honeydew is a sign, which the whitefly has been fed for some days. Also, you might see the ants interested in sweet honeydew.

Are Whiteflies Harmful to Humans?

Are Whiteflies Harmful To Humans 2
Whiteflies and their pupae on a leaf via

Whiteflies don’t bite humans because the mouthparts are designed to penetrate plant matter, not flesh. They often fly when disturbed and are too small for humans to be interested in the culinary manner. The greatest human impact with whiteflies is damage to the crops and other ornamental plants.

When the nymphs and adults feed on the juice, they can weaken the plants due to this feeding manner and the damage they cause when cutting the plant.

Nevertheless, plants are less affected, but this process stimulates the growth of harmful molds and causes the spread of diseases. When the whiteflies begin to feed, they secrete saliva in the cut, bringing in molds and bacteria from other plants.

However, more damaging is the honeydew excretion, which larvae and adults produce as waste products from the ingested sap.

These sugary substances coat the plant’s leaves on which they feed and cause mild growth and other molds. Many species, like ants, eat honeydew as the source of nutrients and sugar.

Whiteflies are challenging to control and very small to fit in the nets placed in greenhouses to prevent pests. Therefore, they are not harmful to humans but irritate farmers and gardeners and can affect agricultural production, leading to low food availability.

Are whiteflies harmful to pets?

Because whiteflies don’t bite, they’re not harmful to pets. Typically, many pets can find small flying insects intriguing or alarming, where they hide from or try to explore them.

But these flies are just starting their day. Since whiteflies are very difficult to remove, many people use pesticides to control them. Nevertheless, some pesticides are harmful to pets.

Which plants are vulnerable to whiteflies?

You can find the whiteflies on many plants, from warm vegetables like tomatoes, eggplants, okra, and peppers to ornamental flowers.

Some species can attack citrus trees, cabbages, and sweet potatoes. Indoors, they get food from common houseplants, particularly those with smooth and soft leaves.

Where to find the whiteflies on the plants?

White butterflies prefer to eat young plants, so first, check the freshly unfurled leaves. Check the leaves’ underside, particularly around the veins, because whiteflies are not easily visible, and feel the surface of the leaves for sticky honeydew. When they eat, they will suddenly fly off the leaves, so it is pretty obvious.

You will also find eggs under the leaves, which is the start of the new generation. Once they hatch, the larvae appear like little white ovals that have no legs.

They do not move but immediately begin to suck the juice from the plants. This is why the gardeners need to trace whiteflies before it is very late.

Adult females can lay about 400 eggs that hatch between one week and one month after laying. Normally, they are arranged in a circle. Newly laid eggs are light yellow and turn brown just before hatching.


Whiteflies are nuisance pests that damage the plants. However, they are not harmful to humans and animals. They’re the best food source for different animals, starting from damselflies to ladybirds and even some species of birds.

Although we may not be grateful to see whiteflies on the plants or the farmland, at least they’re not harmful to humans, which means they are less annoying.