Mealybugs — Wisconsin Horticulture

Wisconsin Horticulture

Division of Extension

Mealybugs

Karen Delahaut, formerly UW-Madison Fresh Market Vegetable Program
Revised: 4/26/2004
Item number: XHT1129

Mealybugs are slow-moving, small, oval insects that are covered with a white, cottony wax. They are tropical insects that are typically only found on perennial foliage plants, and rarely on flowering or bedding plants. They can infest all plant parts including the roots. Mealybugs are related to scales. The citrus mealybug (Planococcus citri) is the most common greenhouse species and is the most damaging.

Appearance: Mealybugs are pink, soft-bodied insects that range in size from 1/20 to 1/5 of an inch. They are somewhat elongated and segmented and have waxy filaments extending from their hind end, giving the appearance of a tail. They are covered with a white or grey cottony wax. Because of their appearance, mealybugs may be confused for cottony cushion scale or wooly aphids. Unlike their close relatives the scales, mealybugs retain their legs throughout their life.

Symptoms and Effects: Mealybugs feed at stem tips, and where the leaf meets the stem. The citrus mealybug is more common on tropical foliage plants or soft-stemmed, succulent plants such as coleus, fuchsia, and cactus. Long-tailed mealybugs prefer dracaena over other species. Symptoms of mealybug feeding include stunting, chlorosis, defoliation, and wilting. Because mealybugs feed on sugary plant juices (photosynthates), their waste contains a high sugar content and is referred to as honeydew. Honeydew is sticky and can support the growth of sooty mold fungi, which are not harmful to the plant, but if present in high enough concentrations, can impair photosynthesis in the leaves. Citrus mealybugs cause additional problems by injecting a toxin as they feed.

Life Cycle: Mealybugs lay up to 600 small, yellow eggs in a protective cottony mass. Egg-laying is temperature dependent with fewer eggs laid at high temperatures. Long-tailed mealybugs don’t lay eggs, but bear live young in a manner similar to aphids. After laying eggs over a period of five to 10 days, the female dies. Young female mealybugs go through three instars (stages) and are mobile their entire lives. Immature males (nymphs) settle and spin a white, waxy cocoon. Adult males are tiny and winged, but rarely seen, and only live a few days. One generation develops every one to three months depending on temperature.

Scouting Suggestions: Visually inspect the leaf whorls of susceptible plants. Long-tailed mealybugs can often be found in whorls. Examine any white mass carefully to determine whether it is a mealybug, a mealybug egg mass, or the larval stage of the beneficial mealybug destroyer (see below). Yellowed or wilted foliage may indicate an underground mealybug infestation. This is particularly common in African violets. Check for white cottony masses around drainage holes to determine whether a closer inspection of the roots is necessary.

Control:
Non-Chemical: The best mealybug management is avoidance. All new plant material should be inspected upon arrival and any infested plants should be returned to the supplier. Destroy heavily infested greenhouse plants as they will be difficult, if not impossible, and very costly to clean up. Remove any excess soil and compost piles from the growing area to prevent an alternative infestation site.

Mealybug destroyers are a type of beetle that can be very effective in controlling mealybug populations in some situations. However, for this technique to be effective, you must be willing to tolerate a low level infestation of both pests and beneficial insects on your plants.

For more information on biological control, refer to NCR publication 581 “Biological Control of Insects and Other Pests of Greenhouse Crops”.

Chemical: There are several insecticides available for control of mealybugs. Refer to UW-Extension publication A3744 “Insect Pest Management for Greenhouses” for a complete listing of available products. Chemical control will be difficult because of the protective nature of the wax covering the insects. Contact sprays using insecticidal soaps are affective against the mealybug crawler stage provided coverage is thorough. Use insect growth regulators when beneficial insects are present. You will need two to three treatments at 10-14 day intervals to get good control, as the eggs and adult stages are protected from most insecticides.

For more information on mealybugs: See UW-Extension Bulletin A3744, or contact your county Extension agent.

hort.extension.wisc.edu

Master Gardener Program

Division of Extension

Mealybugs

A dense colony of mealybugs.

Mealybugs are common pests of houseplants. They are pink, soft-bodied insects covered with a white, waxy, cottony material. The white “fluff” helps protect them from excessive heat and moisture loss. Unlike their relatives the scales, most species retain their legs throughout their life and can move around. Females are rounded, wingless, and about 1/16″ long.

The citrus mealybug (Planococcus citri) is the most common species found on plant foliage. It feeds on a wide variety of plants, and especially likes soft-stemmed and succulent plants such as coleus, fuchsia, croton, jade, poinsettia and cactus. In my greenhouse I also find them consistently on rosemary, citrus, and bird of paradise. Other mealybug species such as longtailed mealybug (P. longispinus) or cactus mealybug (Hypogeococcus festerianus) occasionally occur on specific host plants. These species remove plants sap from aboveground plant parts, especially stem tips, leaf junctures and new growth.

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Citrus mealybug, the most common species of mealybug found on houseplants.

Their feeding weakens and stunts plants, and causes foliar yellowing, defoliation, wilting and general plant decline. In some cases, plants can be killed. Citrus mealybugs inject a toxin while feeding that causes plant malformation. Mealybugs also excrete honeydew, which allows for the growth of sooty mold.

Some mealybugs are root-feeders. The ground mealybug (Rhizoecus falcifer) is the most common soil mealybug, occurring on the roots of many house plants, especially African violets. Feeding on the root hairs results in yellowed leaves, wilting, stunting and bloom reduction. A few mealybug species will move to roots when growing conditions are less favorable, but return to stems and leaves when plants are actively growing.

A female mealybug and her cottony egg mass.

Female citrus mealybugs lay up to 600 small (1/100 inch or 0.3 mm long), yellow eggs within a protective mass of white, cottony threads. The longtailed mealybug does not lay eggs but produces live young, similar to aphids. After depositing the egg mass or live young over a period of 5–10 days, the female mealybug dies. The immatures search for feeding sites on which to settle. Male nymphs settle and spin an elongated, white waxy cocoon. Females have three instars and are mobile throughout their lives.

Citrus mealybug egg mass with newly hatched nymphs.

The best method for detecting infestations of mealybugs on leaves and stems is visual inspection – just looking at the plants. Both the insects themselves and the eggs in their masses of waxy threads may look like white cotton on the plant. On some plants mealybugs concentrate on the growing tips, and on other plants they are more dispersed. The longtailed mealybug frequently conceals itself in leaf whorls.

Underground infestations are more difficult to detect. Yellowed or wilting foliage may indicate the presence of mealybugs on the roots. Small white cottony masses around the drainage holes of pots also indicate the presence of mealybugs, but in many cases infestations can be confirmed only by removing the root-ball from the pot to observe mealybugs on the roots.

Control

Mealybugs on a hibiscus flower bud.

Mealybugs are difficult to get rid of because immatures typically wedge themselves in stem crotches, leaf folds, or other tight locations where washing or pesticides cannot reach them. The best way to control mealybugs on houseplants is to prevent them from being established in the first place. Carefully inspect all new houseplants before introducing them to your home, and keep them separate from other plants for a week or so if possible. Mealybugs can easily crawl from one plant to another, especially when leaves or branches overlap, so one contaminated plant could spread mealybugs to all your houseplants. Check under leaves, in new leaf folds, and around the growing tips for signs of infestation. Mealybugs like lush foliage, so avoid over-fertilizing with excess nitrogen.

A citrus mealybug nymph crawls along a leaf.

If mealybugs are present on only a few, small plants, you can try to reduce or eliminate infestations by washing off the plants. A moderately strong spray of warm water will dislodge most of the mealybugs. Alternatively, you can try wiping the insects and egg masses off the plants with a cotton swab or cloth dipped in rubbing alcohol. This is most effective on large-leaved plants (but test first on a small area to make sure the alcohol won’t damage the plant; it may take a day or two for symptoms to show). Washing rarely eliminates all the pests, so it is important to check the plants periodically and wash again or use other controls when more are noticed.

A mealybug crawls on a red coleus plant.

It may be helpful to prune out heavily infested plant parts when such pruning won’t damage the appearance of the plant. Dispose of plant cuttings immediately, since mealybugs can survive on detached plant parts for as long as those parts have moisture. Consider discarding a heavily infested plant and replacing it with a new, pest-free plant as one way to deal with a severe mealybug problem. Root infestations are particularly difficult to control, so this is often the most practical way of eliminating root mealybugs.

Chemical controls can be used to treat mealybugs. Less toxic alternatives such as insecticidal soap or horticultural oils can be effective, but must be applied to the hard-to-reach places the mealybugs inhabit to kill the insects. These may require several applications to achieve control. There are several registered insecticides available at garden centers that will control mealybugs. Read the label carefully to make sure the material is effective for mealybugs and for instructions on how to apply the pesticide.

A citrus mealybug.

A number of natural enemies, including several parasitic wasps and predators, are known to attack mealybugs. Some are used for control of mealybugs in commercial greenhouses, but most are not appropriate for use in the typical home. The mealybug destroyer, Cryptolaemus montrouzieri, is a small lady beetle that is a very effective predator, especially when mealybug numbers are high and many egg masses are present. It can be purchased commercially and should be released at the rate of 2-8 adults per plant. However, it will take some time for the beetles to reduce mealybug populations and may not eliminate it entirely.

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– Susan Mahr, University of Wisconsin – Madison

wimastergardener.org

BEST Ways To Kill Cyclamen Mites On African Violets

Cyclamen mites are the common predators of African violets, you need to kill them when found. African violets are amongst the well-known house plants in the world. These are attractive and grow in a variety of sizes, from miniatures to a full-fledged plant. People love to decorate their indoors with African violets.

But there are predators to your African violet, that you must know how to get rid-off. One of the commonly found pests is “cyclamen mites”.

How do you kill cyclamen mites on African violets? Cyclamen mites can be killed by using certain miticides such as Kelthane and Thiodan. Prevent contact between each plant to stop spreading.

There are many types of mites common to flowering plants such as cyclamen mites, two-spotted mites, and broad mites. Mites feed by penetrating plant tissue with their mouth-parts and absorbing out cell contents.

You may often be unaware of cyclamen mites until you see the damage caused by their feeding on plant tissues because the mite can’t be seen through the naked eye.

Signs of cyclamen mite attack:

You may find the damage near the buds or spread the entire plant. The damage includes:-

  • Inward curling of the leaves.
  • Squeezing or wrinkling of the leaves.
  • Extreme hairiness on the younger leaves of the African violets
  • Pit-like depressions may form that gives leaves a wrinkled appearance.
  • Leaves may also become brittle.
  • Foliage may become darker and appear streaked.
  • African violet flower buds may not open or flowers can become faded or become discolored.

Your African violets are not only in danger!

  • The cyclamen mite has a broad host range. Besides African violets, some of the other commonly infected plants are dahlia, gloxinia, ivy, snapdragon, chrysanthemum, geranium, fuchsia, begonia, petunia, and azalea.
  • Recently cyclamen mite damage has been especially noted on snapdragons, kalanchoe, Exacum and hydrangea. Outdoors, this mite can attack delphinium, aconite, dahlia, chrysanthemum, verbena strawberry, and viola.
  • Delphinium is particularly severe in damage, as flower stalks become twisted and knarled and buds turn black and do not open.

Temperature:

Cyclamen mites tend to prefer a temperature and are mostly active at 60 degrees Fahrenheit, which implies, it causes more damage during fall or winter months.

However, you may frequently confuse broad mites with the cyclamen mites because they both cause damages that are closely related.

How to distinguish a Broad mite from Cyclamen mite?

  • However, you can distinguish on the basis of temperature where broad mites are mostly active at 70 to 80 degrees Fahrenheit as compared to cyclamen mites mostly active at 60 to 70 degrees Fahrenheit.
  • The cyclamen mite also tends to feed on the lower leaves of African violets causing a downward crumple of leaves. Broad mite feeding may result in terminal buds being killed but there is a little deformity of the flower buds.

Life Cycle of Cyclamen mites:

The adult mites are very small, about 0.0009 inches (0.25 mm) long, so they cannot be seen without a microscope. The adults are shiny, slightly colored orange to brown and elliptical in shape. They prefer to hide in buds or deep within the flowers.

  • An adult female can lay two to three eggs per day for up to two to three weeks.
  • The eggs are deposited in moist dark places at the base of the plant and in cracks.
  • The majority of eggs will develop into females.
  • The young larvae are highly active for about one week.
  • Cyclamen mites complete their life cycle from egg to adult in about two weeks at a temperature of 60 degrees Fahrenheit.
  • The adult female in the winter can also stay and lay eggs in protected locations such as Leaf covers in old crowns of strawberries.

Physical methods to kill Cyclamen mites in African violets:

The physical control of Cyclamen mites includes two important parameters:-

These are the important components of management against cyclamen mites.

Mites can easily spread from infected to non-infected plants by plants’ contact, workers hand, or by infected gardening tools.

Physical methods to prevent damage by Cyclamen mites?

  • It is best to prevent or discard the infected African violet plant since these mites can be difficult to control and reproduce rapidly. Hence, start over with a clean and healthy plant.
  • Sanitation defines a review of a newly purchased plant in the spring and rejects them if you find curled or deformed tips and shoots that may be signs of mites.
  • During the assessment of pest attacks and other routine tasks on African violet, enter the infected plant area last in order to avoid mites attack over healthy plants.
  • Use hot water treatment to kill mites. Dip infected African violets into water held at a temperature of 110 degrees Fahrenheit for fifteen minutes to destroy the mites without damaging the plants.
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Initial try this technique on a small scale because different varieties of African violet may vary in their sensitivity to this treatment.

If you treat small numbers of African violets, then trim off badly injured plant leaves before dipping it in water. It is better to dip the entire plant and pot into the water.

Chemical methods to kill Cyclamen mites in African violets:

  • Treat the infected plants with miticidal/ insecticidal soap or horticultural oil.
  • You must spray completely to cover the insects spread across the plant. So apply liberally and make sure the spray reaches under leaves and into shoot tips where the mites hide.
  • Use a chemical spray such as “Dicofol”- a widely used miticide can give good control. You can also use certain miticides such as Kelthane and Thiodan may against cyclamen mites.

Biological methods to kill Cyclamen mites in African violets:

In general, there is an increase in Cyclamen mites populations due to varieties of plants grown in a greenhouse or nursery.

  • Biological control involves mites, who kill mites. It means biological control of cyclamen mite is another management option that involves the use of commercially available predatory mites.
  • The predatory mite, “Neoseiulus cucumeris”, and “N. californicus” have been utilized to suppress cyclamen mite populations on certain African violets when grown in a greenhouse.
  • It is important to apply predatory mites African violets early before the approaching winter, to prevent an increase in Cyclamen mite population.

Related Questions:

Can you grow African violets in the ground?

No, African violet is purely suitable for in-house conditions due to the following reasons:-

  • African violets are easily susceptible to pests and diseases, under direct exposure to the environment.
  • Leaves of African violets become dark and crumbled under direct sunlight. Hence indirect sunlight is suitable which is ideal for indoor conditions.
  • The extreme weather condition in winter and summer are not suitable for African violets, as it usually dies. A moderate temperature is mostly preferred for its growth, hence in-house conditions are ideal for it.

How can I get rid of mealy bugs on my African violet?

It is difficult to get rid of mealy bugs because spraying injures the foliage.

  • Watch for the first signs of these white woolly sucking insects and remove them with a small brush dipped in alcohol.
  • Touch only the bag, not the leaf.
  • Avoid too hot or dry atmosphere. A house plant aerosol bomb is also effective.

What causes a mold like covering over the topsoil of house plants, particularly African violets?

The following reasons like:-

  • Insufficient aeration.
  • Cultivate the soil occasionally with the tines of an old fork. Too much water compacts compact the soil and encourage the mouldy surface growth.
  • You may need to re-pot with afresh mixture.

Is there any remedy for lice on African violets?

The remedy for lice on African violets is:-

  • Constant vigilance over the plant
  • Pick up the cotton fluff or touch each insect with a small swab of cotton on a matchstick dipped in alcohol.
  • A malathion spray will control mealy bugs.

How to get rid over small insects in African violets, that weaves a white web all over it?

It is probably a mealybug, and if the infection is that bad, you would better burn that plant and start with a healthy one.

What do you do for whiteflies on ageratum?

  • The whiteflies usually come along when you get your plants from the greenhouse, in the spring and cause minute white spotting of the foliage all summer, getting worse toward fall.
  • Frequent spraying with nicotine sulfate and soap or malathion hitting the underside of the leaves.

What is the best method to prevent wire-worms?

  • Use a newly broken sod, plow it thoroughly and then apply grub proofing material.
  • To help to control wire-worms; with a growing crop, water the grub proofing material into the soil.

How shall I get rid my soil of grub-worms?

  • Do not plant garden crops on turg land or land grown up to weeds and grass the preceding year.
  • If you prefer to use such land, plow in the fall or spade, and apply grub-proofing chemical.
  • Legume crops will suffer less than corn or potatoes.

What is the best lawn seed to use?

  • The best lawn seed to use like Merion bluegrass, generally in a mixture of Meadow Fescue, and red top.
  • You can renew Perennial Ryegrass every year.
  • By all means by the best seed obtainable from a good seed house.

Conclusion:

Cyclamen mites seem to avoid the light. They occur in hidden areas on plants (buds and between the calyx and corolla and the stamens and ovaries of flowers). This mite also prefers high humidity.

Moreover, precisely examine isolated places in plants and follow the aforementioned procedure to kill Cyclamen mites in African violets. Take appropriate precautions while applying miticide/insecticide sprays.

plantinguide.com

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