The whitefly does not mean the accessory of a suit but a widespread plant pest. This supposedly appears out of nowhere and damages useful and ornamental plants. In order for control measures to be successful, it makes sense to take a look at the way of life.

The whitefly belongs to the whitefly family

Table of Contents

Show all
  1. the essentials in brief
  2. Combat naturally - home remedies
  3. Evict and keep away
  4. Home remedies don't help
  5. Combat with chemicals
  6. Commonly infested plants
  7. development and threat
  8. frequently asked Questions

    9. the essentials in brief

    • Rapeseed oil preparations and soft soap (44.90€) are effective home remedies to combat whitefly. Various plants are effective because of their essential oils or toxic ingredients.
    • Measures often do not achieve the desired success because the plants are weakened by incorrect care or location.
    • Ichneumon wasps (€22.99) are beneficial parasites and represent an environmentally friendly alternative to chemical pesticides.
    • A handful of species affect specific plants, and almost any crop can be affected. They live on the underside of leaves and are endangered by a naturally occurring fungus.

    Fight whitefly with home remedies

    If you want to combat whitefly, consider hosing down your plants with a strong jet of water. This measure works for hard-leaved or succulent plants. Soft-leaved plants should be wiped off with a damp cloth. Then it is necessary to treat the plants with home remedies.

    Combat whitefly: rapeseed oil

    Rapeseed oil only harms whiteflies, it is harmless to beneficial insects, humans and pets

    Rapeseed oil preparations are suitable for indoor and outdoor use because they are gentle on beneficial organisms and harmless to humans and pets. Mix a rapeseed oil preparation with water and spray the remedy regularly on the affected leaves. The pests are trapped under the oil film and suffocate. Since the spraying can clog the stomata of the leaves, you should rinse off the plants after allowing them to take effect. This is especially true for indoor plants, where the oil film does not dissolve due to natural weather influences.

    soft soap

    The product is made from rapeseed oil and caustic potash and is corrosive to the skin of soft-skinned insects such as whiteflies. Since it is classified as a plant protection product, you are not allowed to make soft soap yourself. You can buy soft soap commercially and prepare an aqueous solution to use as a spray:

    • Dissolve a tablespoon of soap in a liter of rainwater
    • spray directly onto the pests so that leaves are dripping wet
    • Insects die in their sucking posture and remain on the leaves after death

    When using it, you should make sure that the fine mist does not get into your eyes. The mucous membranes become irritated and burn easily. If soft soap is dissolved in hard water, a kind of lime soap is formed. It is less suitable for pest control and easily clogs spray bottle nozzles. Dishwashing liquid and curd soap are not alternatives to soft soap because they are based on caustic soda. This is considered to be less compatible with plants.

    Plants as anti-fly agents

    The plant kingdom has developed natural substances that automatically keep pests away. Although planting such plants out does not completely protect against insect infestation, they do greatly control populations. Beneficial creatures and insectivorous predators can finish off the remaining whiteflies.

    Plants with special ingredients:

    • zinnia: Zinnias contain nicotine and attract predatory insects that eat whiteflies
    • Nicandra: Blue physalis contains alkaloids and withanolides that reduce pest infestation
    • Monarda: Indian mint, bee balm, wild bergamot or peppermint contain vexing essential oils
    • tanacetum: Dalmatian insect flower produces pyrethrins that paralyze the nerve center

    Repel and keep away whiteflies

    So that the annoying pests do not appear, you should make your garden as versatile as possible. There are some plants that have a natural repellent effect on whiteflies. These are either suitable for planting in the greenhouse and garden, or can be used to produce sprays.

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    Essential Oils

    Whiteflies can be driven away by essential oils from intensively scented herbs. Since the fragrances are quickly volatile, you should repeat the measures regularly and renew the herb. Fresh plant parts are more effective than dried herbs. To extract the essential fragrances, you can brew a brew from the herb. Essential oils are the basis for sprays:

    • Add mint essential oil to water
    • Mix one liter of rainwater with one drop of dish soap and ten drops of lavender oil
    • Finely chop two cloves of garlic and pour hot water over them
    • Pour 1 liter of boiling water over 100 grams of tansy

    Mixed cultures against whiteflies

    If you combine cleverly, you don't have to worry about pests

    Some plants have proven to be natural pest repellents when placed in appropriate intercropping. The vitality of the plants plays an important role. In order for such anti-pest plants to develop their full effect, they must be properly cared for. If they suffer stress from drought, waterlogging or a lack or excess of nutrients, the plants themselves develop into fly magnets. Basil makes an excellent underplanting to keep whitefly away.

    Anti-whitefly mixed culture Bad neighbors
    cabbage Thyme, Peppermint, Rosemary, Pineapple Sage Strawberries, Garlic, Mustard, Onions
    tomatoes Garlic, lavender, nasturtium fennel
    cucumbers Dill, celery, leek, cumin radishes, tomatoes
    strawberries Lettuce, Indian Spinach, Thyme cabbage

    parasitic wasps

    With beneficial insects such as the parasitic wasp Encarsia formosa (short: EF parasitic wasp) you can biologically combat the most common whiteflies. Identify the pest beforehand to find the right parasitic wasp. The insects are 0.5 millimeters in size.

    Females have a ovipositor that they use to pierce whitefly larvae and lay their eggs. The larvae that hatch eat the host from the inside, turning the larvae black. After a week, the parasitic wasps hatch. One insect can destroy up to 300 whiteflies.

    Application:

    • Place cards with parasitic wasp larvae between the plants
    • at temperatures of at least 16 degrees Celsius and a humidity of 60 percent
    • not suitable for winter months due to lack of light
    • after whiteflies have been fought, parasitic wasps die off

    When home remedies don't help

    Whiteflies prefer moist, warm locations

    Whiteflies prefer high humidity and temperatures above 23 degrees Celsius. They do not like draughts, but look for windless and sheltered areas in dense plant populations. Plants in very dry or cool places are avoided. If your plants are suffering from the pests despite numerous control measures, environmental conditions could be a cause.

    Increased infestation after spraying

    Frequently the infestation seems to increase after the control measure. This is because the environmental conditions change as a result of spraying and the pests produce more eggs. Therefore, repeat spraying with rapeseed oil or soft soap solutions at intervals of ten to 14 days.

    Constantly recurring infestation of indoor plants

    It is not uncommon for the pests to be very stubborn and no control measures bring the desired success. Individual eggs often survive in the leaf axils or in the folds of rolled leaf edges. Place the affected plants on the balcony or terrace during the summer months and let beneficial insects work for you. Bring sunscreen to keep the leaves from burning.

    If whiteflies keep coming, a change of location should be considered.

    Whiteflies on basil

    The pests often appear on herbs in the greenhouse, although the infested plants actually have a deterrent effect. Basil is a good example of this dichotomy. In a healthy condition and with optimal care, the herb grows vigorously and proves to be an effective deterrent. Weakened and ailing plants or specimens that are in suboptimal locations are more likely to suffer from whiteflies. Two species occur in the greenhouse: greenhouse whitefly and cotton or tobacco whitefly.

    Getting basil pest-free:

    • with at least six hours of sunshine, the sorrowful aroma unfolds optimally
    • a cooler location with temperatures below 18 degrees reduces the number of flies
    • a change of location to a well-ventilated place drives away the pests

    Rapeseed oil is ineffective

    Commercial rapeseed oil does not dissolve in water without an emulsifier, so a few drops of oil in water do not make a suitable spray. Canola oil supplements contain soy lecithin, which acts as an emulsifier, dissolving the oil in water. Dishwashing liquid has a similar effect, but the exact mixing ratio and the speed of mixing are crucial. An oily film does enclose the insects. Oil droplets still tend to drip off, so an ecological adhesive such as Break-Thru should be mixed in.

    Preparation of an oil-water solution:

    • Mix ten milliliters of rapeseed oil with half a shot glass of dish soap
    • add a small sip of water
    • slowly add 1 liter of water while mixing constantly

    Fight whitefly - with chemicals

    There are numerous chemical agents against whiteflies. Many are based on potassium salts and have the same effect as an aqueous soft soap solution. Other products contain canola oil and are expensive compared to homemade canola oil sprays. Various neurotoxins are added so that the products work better than household remedies.

    Common neurotoxins in sprays:

    • Acetamiprid: nicotine-like active substance, approved for potted, ornamental and vegetable plants
    • Deltamethrin: pyrethroid, approved for cereals, meadows, potatoes, oilseed rape and beets
    • Methiocarb: no longer approved as an insecticide due to high toxicity
    • Thiacloprid: nicotine-like active ingredient to combat crop and fruit pests
    • Pyrethrine: Natural substance with insecticidal effect

    However, such neurotoxins are not beneficial to beneficial organisms. They not only kill pests, but also wild bees, bumblebees or important pollinators and endanger birds or aquatic life. When used in your own garden or house, they impair the health of pets and humans. Therefore, refrain from using chemical agents and resort to effective home remedies or make use of mechanical measures.

    Types of commonly infested plants

    The greenhouse whitefly is just one of about 80 species of whitefly

    Whiteflies are not picky about food. They are polyphagous and come in species from more than 80 different families. The term whitefly stands for the whitefly family and includes more than 1,500 species. Many of them prefer certain plants, which can be seen in their common German name. The cabbage whitefly is a common whitefly on cabbage.

    tips

    You should fight the whitefly in cool weather in the morning. At lower temperatures, the insects are less active.

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    Recognize an infestation

    The first adult pests are easy to detect. When you touch the leaves, they fly up quickly. Their body is covered with a mealy dust of wax particles, which makes the insects appear comparatively conspicuous. It is produced by abdominal glands and makes the body look white.

    Whiteflies are plant lice and have four wings. They leave a sticky secretion on the leaf surfaces, which is an ideal breeding ground for sooty mold fungi. The sucking activities weaken the plant. If whiteflies occur in masses, yellow spots appear on the leaves. These gradually wither and fall off if the insects are not controlled.

    scientific colloquial preferred plants parasitic Encarsia species
    Whitefly Siphoninus phillyreae Ash White Fly Ash, apple, pear and quince trees, citrus trees E. inaron
    Greenhouse whitefly Trialeurodes vaporariorum Greenhouse Whitefly ornamental and useful plants, indoor plants E.formosa, E.lutea
    silver fly Bemisia tabaci Tobacco Whitefly Vegetables and fruits of various plants, e.g. tobacco, tomatoes, poinsettias E. bimaculata, E. lutea, E. sophia, E. pergandiella,
    cabbage whitefly Aleyrodes proletella White fly on cabbage Cruciferous vegetables such as alfalfa, clover or cabbage E. tricolor
    citrus whitefly Dialeurodes citri Lemon White Fly citrus E. lahorensis

    Damage to indoor plants

    The plant pest Trialeurodes vaporariorum occurs primarily in plants in rooms or greenhouses. After the females lay their eggs on the underside of the leaves, the larvae hatch and feed on the plant sap. They excrete honeydew, so the undersides of the leaves are covered with a sticky film. Sooty mold fungi can settle here if the humidity is high. A brief change of location to an airy place can help. You should treat sensitive plants such as orchids with a water jet.

    tips

    Do not buy plants that have been treated with Confidor. The pesticide contains the active ingredient imidacloprid, which drives parasitic wasps away.

    plants in the garden

    When combating plant sap suckers, you should not just focus your attention on the affected crops. Expand your view of the entire plant population. In the garden, vegetable plants are often affected by the pests when the microclimate provides favorable conditions. The insects mainly attack weakened and ailing plants. Annual herbs and balcony flowers are particularly affected. Whiteflies do not stop at ornamental plants and woody plants. Occasionally weeds may show an infestation.

    Commonly Affected Plants:

    • vegetables: turnip greens, cucumbers, broccoli
    • shrubs: roses, hibiscus, boxwood
    • ornamental plants: petunias, rhododendrons
    • fruit perennials: Strawberries

    development and threat

    Whiteflies can reproduce both sexually and asexually. The females place their eggs on small stalks on the underside of the leaves, arranging them in a ring. A layer of wax protects the eggs from drying out, while the stem ensures water absorption.

    larval stages

    Females hatch from the fertilized eggs, while males emerge from unfertilized eggs. The newly hatched larvae are initially free to move so that the offspring can spread. Only the following three stages are immobile. In these phases, the larvae are firmly attached to one point and protect themselves with a thick layer of wax. After the fourth larval instar, the organisms pupate.

    Natural enemy in soil

    A global fungus that occurs naturally in the soil poses a threat to whitefly. The spores of the species Beauveria bassiana adhere to the outer skin of the pest, allowing the fungal hyphae to grow into the insect after germination. They spread and deprive the harmful insect of nutrients and water. Larvae are particularly susceptible to the fungus, which also affects eggs and adult whitefly. As a result, this fungus proves to be a useful weapon against the pest.

    frequently asked Questions

    How do I recognize a whitefly infestation?

    The whitefly is small, but you can see it with the naked eye

    If you spot yellow spots on the leaves, you should inspect the undersides of the leaves.The adult flies quickly flee when the leaves are moved. Females lay their eggs in characteristic rings. The larvae are freely mobile in the initial stage and can be recognized by their whitish coloration with yellow, greenish or brownish nuances. In the later larval stage, they attach themselves to the underside of the leaf and are reminiscent of smallpox. Often you will discover different stages of development on the underside of the leaves.

    Typical signs of an infestation:

    • Leaves yellow and eventually fall off
    • Plant suffers from stunted growth
    • Fruits are misshapen

    What helps against the whitefly?

    You can fight whitefly with simple methods. Home remedies should be the first choice because they often make chemical agents superfluous. An aqueous solution of soft soap has proven to be an effective remedy. Essential oils have a deterrent effect and keep insects away from your plants.

    If the infestation is so severe that even home remedies no longer help, you should use beneficial insects. Ichneumon wasps are among the most effective means of combating whiteflies. They lay their eggs in their larvae and kill countless offspring within a short time. It is important that you use the correct species of parasitic wasp. Each species prefers different host insects.

    Whiteflies on kale - still edible?

    Basically, the cabbage is edible, since neither the pest nor its secretions are poisonous. Eggs and larvae usually cannot be washed off completely. They provide an additional source of protein, but can cause feelings of disgust in sensitive individuals. The honeydew disappears when cooked. Favored by increased humidity, the film can be colonized by sooty mold fungi. Check the kale for rotten spots or black discoloration. If fungi have settled, the vegetables should no longer be eaten.

    What are those white flies in the potting soil?

    If you spot white insects in the potting soil that crawl out of the substrate after watering, they are springtails. These insects are one to three millimeters in size and wingless. They break down dead plant matter and are not harmful to your houseplants. The insects were probably brought into the planter with the compost, because they prefer to live on the compost heap. Here they turn out to be useful organisms involved in the production of humus.

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Animals in the garden