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Controlling Mealybugs on Orchid

Ailments

by Anu Dharmani

Originally published in BellaOnline

Posted by Sys Admin almost 4 years ago.

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It is now mealybugs turning up to trouble me and my plants, though luckily enough it was one plant ‘Tecoma’ (yellow bells, ghanti phul) which was attacked. My orchids are safe for now, but in case orchids also get infected by these pests then there are numerous ways to get rid of them. 

Mealybugs attack many plants, including orchids especially Phalaenopsis and are among . These pests are gray coloured having soft bodies which is covered by white cottony mass. 

Where to find them 
1. These appear as tiny balls of cotton on the leaf axils. You might even find them on the stems, stem joints, or even the underside of the leaves. 
2. In the preliminary stages of infection, they occur at the leaf axils. 

Damage Caused by mealybugs 
1. As they suck the nutrient containing sap from the plant, it weakens the plant. You will find the leaves drying and falling, same will happen to the flowers. 
2. They form associations with ants. Ants get nectar from the mealybugs while in turn ants protect the bugs from predators. These ants can cause extensive damage to the flowers and soft new leaves. 

How to Control the infection
1. It is very important to isolate the infected orchid, otherwise the pest will spread to other healthy plants as well. 
2. These pests can be controlled biologically by introducing natural enemies like the ladybird (especially, the spotless type), parasitic wasp, lacewings (beware, these can give irritating bites too). These are commercially available. 
3. Neem oil is also helpful in controlling these pests. Four to five teaspoons of neem oil can be mixed in four litres of water and can be sprayed on the infected orchids. I came across an effective home remedy of spraying a mix of garlic flakes and mineral oil on the mealybugs. 
3. Using insecticidal soap or rubbing isopropyl alcohol on affected areas can be helpful. 
4. It is difficult to control mealybugs in orchids, using chemical based pesticides. However, spraying parathion or malathion on mealybugs has shown some results. Please use insecticides only in case of large scale pest infections. 
5. Repeat these control methods after three to four days, depending upon the scale of infection. Insecticides should be used according to the instructions provided on the container. 
6. In my case, I removed the infected areas of the plant (leaf axils and some portion of the stem) along with the mealybugs. The bugs have not returned since three weeks now (though my fingers are still crossed!). 

Points to keep in mind 
1. Ants are known to from friendly association with mealybugs. Ants deterred the natural enemies of mealybugs, so controlling ant populations is important for effectively controlling the mealybugs by biological methods. 
2. Use only clean sterilized tools while working with plants. 
3. When watering do not leave the orchid in water for very long. If you are watering orchids by dipping them in water then make sure that they dry off, especially the leaves and stems. Dipping in water should also be avoided during hot and humid weather conditions. This is because extra water on the orchid is like and open invitation to pests and bacteria.

Note: Restrict the use of chemical pesticide. Many insecticide producing companies are hiding the facts from us about the harmful effect of these chemicals on other insects, especially the bees! If you are planning to use biological and chemical control methods side by side then you might see only a limited success. As the chemical pesticides do not discriminate between friendly and harmful insects. 

Resources 
1. McKenzie, Howard Lester. 1967. MealyBugs of California: With Taxonomy, Biology, and control of North American species (Homoptera, Coccoidea, Pseudococcidae).Berkeley, California: University of California. 
2. Flint. ML, Dreistadt. SH, and Clark, KC. 1999. Natural Enemies Handbook: The Illustrated Guide to Biological Pest Control. UCANR Publications.

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