Pests on orchids – scale insects, mealybugs & Co

Pests are often brought in when you buy a new one. This does not only apply to the inexpensive specimens in discounters and DIY stores with garden centers. This can also happen to experienced orchid growers. It is therefore worth taking a close look at the plants before buying. If only one pest can be seen, the plant should be left standing, because more of it is guaranteed to be hiding. Even if neighboring plants are affected, you should refrain from buying them. The risk of spread is too great. Once you have the pests, it is very difficult to get rid of them.

Hard-leaved orchids such as Phalaenopsis or Cattleya are mostly attacked. The pests like to sit on the underside of the leaves or the shoots of the leaves, completely inside, difficult to see. The earlier an infestation is noticed, the better the chance of getting rid of the pests.

The fight against orchid pests

Regardless of the pests, it is important that they are detected early. This is the only way to prevent the mass spread. To do this, it is necessary to carefully search the plants each time they are watered to see if there are any suspicious signs anywhere. Over time you develop an eye for it, but it’s quite difficult at first. Often the pests are overlooked, they are masters of camouflage, regardless of whether they are spider mites, woolly, mealybugs or scale insects. They are usually only noticed when there are so many that they can no longer be overlooked, and then it is often simply too late. The orchids can no longer be saved because they are too weak.

Scale insects

Scale insects are difficult to control pests. The pests entrench themselves and their brood under a protective shield and are thus well protected. They are between 0.5 and 5 mm in size. Females have a shield that makes them immobile. Young scale insects, on the other hand, are very agile, male specimens are even able to fly. If the shield is easy to lift off, it is a lid scale insect; if it is firm, it is a bowl scale insect.

• Several thousand species of scale insects worldwide
• Can reproduce massively and quickly
• Propagation mostly by egg-laying, but is also possible with viviparous
• Spreading rapidly

Symptoms
Scale insects damage through their sucking activity. Hard-leaved orchid species such as Cattleya and Phalaenopsis are particularly affected. The female scale insects have a sting. They prick the leaf and suck the juice out of the leaf veins. Secretions are released to the plant, which stimulate biochemical processes. This benefits the lice, but it weakens the plants. The lice also give off fructose. This acts like a breeding ground for fungi, which also spread quickly. It is dangerous that sucking insects often transmit viruses. This damages all plants, not just orchids.

• Leaves of the orchid wither
• Discoloration can be seen
• The leaves are falling off
• Leaves and flowers deform

Countermeasures
Scale insects are often bought at the same time. They are so hidden and well camouflaged that they are really difficult to spot. When you notice them, they have usually multiplied and spread a lot. Especially with inexpensive orchids, it is sometimes better to dispose of the plant before there is more damage to neighboring plants. In any case, affected specimens must be isolated immediately. Fighting scale insects is difficult.

First of all, it is advisable to remove the bracts in order to offer the pests as few hiding places as possible. New populations are constantly developing in these well-protected hiding spots. This is avoided by removing the bracts from around the bulbs. Repotting can also be useful.Pesticides
It is important to use systemically acting agents. These are absorbed by the orchid, spread throughout the plant via the juices and are effective everywhere. No matter where the lice pierce the orchid and where they suck, the poisons take effect there. Externally applied agents can never do that.

• The treatment must be repeated to get rid of the pests newly hatched from the eggs
• Read the instructions for use carefully and comply with the regulations!

Oily sprays Oily agents
should be used with caution. There is a risk that the leaves will die off when treated over a large area because the oil clogs the pores. This is often the case with thin-leaved orchids. In the case of hard-leaved specimens, this is usually not so dramatic. It is important, however, that the plants do not come into contact with sunlight in the near future.

Home Remedies
Sometimes home remedies are sufficient. The chemical club does not always help, because pests also develop resistance quickly.

Soft soap and denatured alcohol A solution of soft soap (15g) and denatured alcohol (10 ml) in 1 liter of water can be very effective. The alcohol softens the skin of the lice and numbs them. However, not all orchids tolerate the treatment. This aggressive solution is not suitable for soft and thin-leaved species. With the other specimens, too, it is important not to spray the solution on, but to apply it directly to the pests with a fine brush.

Oil, washing-up liquid and water emulsion
A spray suitable for almost all orchids is the emulsion of 1 l of water with 2 tablespoons of olive oil and a splash of washing-up liquid. In this concentration the oil is harmless to the orchids.

Apply tea tree oil
to the affected areas with a cotton ball. You should try it at one point first, because some orchids react by shedding their leaves.

Fern
broth Fern broth alone is usually not enough to eliminate nuisances, but can be used as a preventative or accompanying measure. Take 100 g of fresh or dried bracken and put it in water for 24 hours. This broth then has to be boiled for about 30 minutes. Let the broth cool and pass through a sieve. Then it can be sprayed over the orchids twice a week. However, it is advisable to do a tolerance test to see whether the plants can tolerate it.

Mealybugs and mealybugs

Unfortunately, mealybugs and mealybugs are common. The little pests are about 0.5 cm tall and are white, light brown or pink in color. Mealybugs are also covered with a white web of wax, which no longer reveals the actual color. The first thing you notice is the white webs on the plant, which look like small cotton balls. Only when the web is removed can the individual animals and possibly also small yellowish eggs be recognized. Mealybugs, on the other hand, surround themselves with a greasy, powder-like dust.

• Belong to the group of scale insects
• Insects sucking sap
• Preferably sit on the leaf axes of the orchids
• Like to hide under the leaves and the bast layer of the bulbs

Symptoms
Mealybugs and mealybugs suck out plant sap. Depending on the severity of the infestation, this leads to a lack of plant sap and to a weakening of the orchid. In addition, the lice release secretions to the plant, which stimulate biochemical processes. This ultimately benefits the lice again, but it harms the plants. The lice also give off fructose, a sticky substance that can be found everywhere on and under the orchid. These places are ideal breeding grounds for fungi, which, when they colonize, also weaken the plants. Sucking insects such as mealybugs and mealybugs can also transmit viruses.

• Leaves of the orchid wither
• Leaf loss
• Leaf discoloration
• Deformations on leaves and flowers
• Leaves are glued together by the fructose
• If the infestation is severe, the whole plant is covered with white cotton wool

Countermeasures
It is important to isolate the infected orchid first so that the pests cannot spread. If many pests can be seen, the plant is usually too weak to survive the control procedure. Therefore, sometimes it is better to part with such a plant.

Oily sprays Oily agents
should be used with caution. There is a risk that the leaves will die off when treated over a large area because the oil clogs the pores. This is often the case with thin-leaved orchids. In the case of hard-leaved specimens, this is usually not so dramatic. It is important, however, that the plants do not come into contact with sunlight in the near future.

Oil-free agents
Oil-free agents are more suitable for orchids. Here, too, sprays are on offer, but also granulates and sticks, which are brought directly to the roots. They have a systemic effect, that is, the toxins are absorbed by the roots, passed through the plant and absorbed by the lice when they suckle. The funds reach every point of the orchid.

• Maintain a minimum distance as the spray is ice cold and can cause leaf damage through hypothermia
• It is essential to repeat the application
• The times indicated on the packaging must be adhered to, otherwise a new generation of lice will spread
• Granules and sticks often also contain fertilizer. Orchids in particular are often sensitive to the fertilizer salts they contain.
• These agents can usually only be used with hybrid orchids, not with the natural forms.

Home Remedies
Sometimes home remedies are sufficient. The chemical club does not always help, because pests also develop resistance quickly.

Soft soap and denatured alcohol A solution of soft soap (15g) and denatured alcohol (10 ml) in 1 liter of water can be very effective. The alcohol softens the skin of the lice and numbs them. However, not all orchids tolerate the treatment. This aggressive solution is not suitable for soft and thin-leaved species. With the other specimens, too, it is important not to spray the solution on, but to apply it directly to the pests with a fine brush.

Oil, washing-up liquid and water emulsion
A spray suitable for almost all orchids is the emulsion of 1 l of water with 2 tablespoons of olive oil and a splash of washing-up liquid. In this concentration the oil is harmless to the orchids.

Natural enemies
Unfortunately, mealybugs and mealybugs have few natural enemies. These include the larvae of the Australian ladybird. However, the animals need warm, humid conditions and these are unfortunately not ideal in warm living rooms and cold houses, which significantly limits their use.

Spider mites

There are roughly two groups of spider mites, those that form webs and those that do not. Those with webs are called real spider mites. Both are harmful. They also belong to the group of arachnids and in their adult state they have 4 pairs of legs. The pests like to sit on the underside of the leaves.

Spider mites are small, the real ones grow to 0.3-0.5 mm, the others are even smaller. They can be red, green, or a different color, depending on what food they have consumed. Several generations of the animals live in the web of spider mites. In good conditions, they multiply en masse. A new generation is added every 10 to 20 days.

• The pests do not like low temperatures and moist air
• The development of the hatched larvae takes longer.
• The animals are very agile and spread quickly.
• They prefer young, soft-leaved leaves, but are not limited to them

The fake spider mites are not that fast and also live as solitary animals. They come from the tropics and need high temperatures. They also like high humidity. The most common is the so-called orchid spider mite, Tenuipalpus pacificus. A cycle of reproduction can take months, and mass reproduction is rare. However, the insects are so small that they are usually only discovered after a long time and then a few animals are enough to cause serious damage.

• More frequent attacks on old leaves
• These look like they are infected with fungus. Yellowish or brownish, sometimes black spots, areas sharply delimited, without transition as with mushrooms
• Like hard- and soft-leaved orchids
• Settle on the leaf surface, but also like on the underside
• Premature yellowing of the leaves
• Particular risk to plants that are cultivated all year round under constant conditions (greenhouse, showcases and the like)
• Viruses can be transmitted, or fungi or bacteria develop

Symptoms
Spider mites can be recognized by the silvery sheen of the leaves. Real spider mites release a substance to the orchid’s cells after being bitten. This then ensures the dissolution of the cell membrane and organelles. The result is a juice that is absorbed by the animals. Air can penetrate the upper structures of the leaf, creating this silvery color. In addition, the webs become visible over time.

• If you spray the shoot tips, flower bases or the entire orchid with a fine mist of water, the webs are particularly clearly visible.
• In addition, infected leaves slowly turn yellow and fall off
• Fungal attack is possible because the plant is weakened
• Viruses and bacteria can be transmitted

Countermeasures
The simplest thing is to rinse off the spider mites. This has to be repeated several times because you never catch all of the pests. Not all orchids tolerate such a procedure, especially in winter. Diving, on the other hand, is useless, as pests protect themselves with air sacs underwater. Products of the neem tree bring help. These have the advantage that they contain several active ingredients so that the spider mites cannot develop any resistance, which they love to do.

• First of all, it is important to isolate the infected plant
• In the case of the real spider mite, if the infestation is not so strong, it helps to water the orchid and put a plastic bag over it. Everything has to be locked so that the humidity increases drastically. That kills the spider mites. But you shouldn’t do this to the orchid for more than 3 days. Then observe the plant and repeat if necessary.
• Natural enemies can also help, especially “Phytoseiulus persimilis”, a predatory mite. However, not all species of spider mite like them.

Chemical control

• Insecticides are rarely effective. So-called acaricides are better, but spider mites quickly develop resistance to them. They are really clever little animals. You can forget about the remedies after just two applications.
• Spray pesticides help, but you never get all pests. The treatments have to be repeated frequently, which the orchids do not tolerate well.

Frequently asked questions
Which pests can be found in the orchid substrate?
Depending on the composition of the substrate, woodlice, wireworms, centipedes, earwigs, earthworms, snails, springtails, millipedes, sciarid gnats or root mites can occur.

Besides the 3 most common pests, which other pests are found on orchids?
Depending on whether the plants are only inside or outside, weevils, whiteflies, lice, thrips, bed bugs and soft skin mites are possible.