Orchid Pests

As with all growing endeavors, occasionally there are pest problems to deal with. Orchid pests include mealybugs, aphids, scale, thrips, and spider mites. Always keep a close eye on your orchids, it is best to deal with problem pests immediately. When purchasing new orchids or other plants, keep them isolated for a few weeks to avoid any possible infestation of your healthy plants.  

Mealybugs

Mealybugs can also attack the roots and the best thing to do if you have a mealy bug infection is to remove the old potting mixture, clean off all the roots, inspect for mealy bugs and spray the roots with a 3% hydrogen peroxide solution. This is also a good time to remove any old and dead roots. Remember to sterilize your cutting shears before making any cuts.  Orchids are epiphytes, so they do not need to be repotted right away. Hang your orchid in a safe spot and give the roots some daily aerial misting for a few weeks, while continually inspecting for mealybugs on the roots and leaves. Alternatively, you can place some moist sphagnum moss in a pot and lean your orchid in the pot with the roots in contact with the moss. Once you feel confident that you have eradicated the mealybugs, you can now repot your orchid in its favorite medium. 

Scale

Scale is one of those pesky orchid pests that is difficult to deal with. They look like miniature barnacles, they are either white or brown, and can completely kill your orchid and spread to your other plants rather quickly. The females lay as many as 300 eggs. If you find scale on your orchid, remove and isolate it immediately and check your other orchids as well. Always keep new orchids in isolation for a period of 6 weeks to monitor for any potential pests that you do not want to introduce to your collection. If you do get scale on your orchid start by cleaning all the leaves manually with a 50% isopropyl alcohol 50% water solution with a cotton ball.

Be as meticulous as you can, use a qtip to get into the leaf nodes and any crevices. Remove all the potting medium and spray the roots with a 3% hydrogen peroxide solution. After thoroughly and meticulously cleaning your orchid, spray your orchid leaves and stems with a mineral oil based insecticide for orchids or create your own home made recipe with 1% paraffin based mineral oil to water ratio mixed with a few drops of dish detergent to act as a surfactant. Either safely mount your orchid without repotting or put some moist sphagnum moss at the bottom of a pot and lean your orchid in the pot with roots resting on the sphagnum moss so that they can absorb moisture.  Monitor often and retreat if necessary. After a period of six weeks, if you are satisfied that you have eradicated the scale, you can now repot your orchid. 

Spider Mites

Unless you are extremely observant of your orchids, you will not likely notice spider mites until these orchid pests have multiplied and have caused some damage to your plants. There are two types of spider mites, there are regular spider mites and false spider mites. Spider mites damage plants by poking holes in the plants leaf surface to extract the sap. Regular spider mites are recognizable by their white webs, false spider mites are red and very difficult to see. Use a magnifying glass to inspect your plants, especially under the leaves, if you suspect that there is something wrong. There are a number of ways to deal with spider mites

One of the most popular, affordable and effective ways to get rid of spider mites is with a home made mineral oil based insecticide. A home made insecticide can be made by adding 1% by volume of a paraffin based mineral oil such as baby oil to water and adding a few drops of liquid dish detergent to act as a surfactant to mix the mineral oil with the water. It is best to remove the orchid from the growing medium and to spray the roots with 3% hydrogen peroxide. Thoroughly spray the leaves on the top and undersides with the mineral oil insecticide. Wipe all leaves down with a paper towel and re apply the mineral oil solution with a fine mist spray. Remove the orchid from the main growing area and repeat the treatment every 7 days for two to three more weeks. If you are satisfied that the mite infestation appears to have been eradicated, you can repot the orchid in a fresh growing medium. 

Mites can be very difficult to eradicate and they can re appear from outdoors, especially if you keep your orchids outdoors in the summertime. It is possible to use predatory insects to control spider mites and even possibly eradicate them. It is important that if you commit to using predatory insects that you do not use any insecticide. Predatory mites and Lacewings are effective predatory insects that will control a variety of orchid pests, but perhaps not what you want in your indoor garden. If you have an outdoor garden or a conservatory, you may find that introducing predatory insects works for you. Insecticidal treatments will harm the predatory insects, so it takes a commitment to this method if you choose to got this route. 

A third method of treatment is to use a serious chemical insecticide such as Avid. Avid is a toxic chemical and it is important to wear gloves, a mask, and goggles when applying a chemical such as Avid. Avid will work on many species of orchids, but avoid spraying the roots. I have had good success with Avid, it is a treatment of last resort. Two treatments of Avid in combination with thoroughly cleaning the growing area, the growing pots, and repotting in a new growing medium can eradicate mites for the most part. Mites can return through windows or with new plants, so always keep an eye on your plants, it is best to tackle mites as soon as you see them. A word of caution when it comes to using Avid is that although I have had good results with my plants, it could be harmful to some plants, so try on one plant first and wait for a few days to see the results. Also after applying this or any of the other treatments, make sure to keep plants out of bright light or direct sun and provide ventilation such as a fan to circulate air. 

Thrips

Thrips are winged insects that destroy your plants by penetrating the orchid epidermis and sucking on the sap. Like many orchid pests they are hard to see and you will most likely notice them after some damage is done.  They particularly like to suck the sap from new growth such as flower buds, spikes and new leaves. Thrips come in different colors, they can be brown, green, or yellow. They lay translucent eggs which are very difficult to see with the naked eye. While you can try to deal with thrips with insecticidal soaps or neem oil, the best thing to do with a thrip infestation is to attack them with multiple treatments of a systemic chemical such as Orthene. Follow the directions on the bottle and as with all serious chemical treatments make sure you wear chemical waterproof rubber gloves, goggles and respiratory mask. I cannot stress that enough, your skin is porous and will absorb chemicals which are poisonous and can damage your health. 

If you prefer not to deal with toxic chemicals and you either have an outdoor garden, or conservatory it is also possible to deal with thrips with predatory insects, but not everyone wants to deal with predatory insects in their home. Predatory mites and lacewings can devastate thrips and this method can work well in outdoor areas. 

Aphids

Aphids are small green insects about the size of a needle pinhead. They damage your plants by penetrating the epidermis of the plant with their pincer like cornicles, and feeding on the sap. They can also cause fungal diseases, so it is very important to treat them as soon as possible. Fortunately, aphids are one of the easiest orchid pests to deal with. If you find yourself with an aphid infestation, start by hosing off your plants (in a sink, so that they do not go into your garden). This will knock down a large portion of the aphid population. Follow this up with a thorough spraying with an insecticidal soap or homemade insecticidal soap. Do this on a weekly basis for two to three weeks and that will usually take care of the aphid infestation.