First, an explanation of what these critters are and what they do. Mealy Bug is an immobile bug in its adult form that take on the look of cotton when in mass groups. They usually attach themselves to stems and leaves of plants, where they then suck on the plants sugars through a piercing mouthpart. The end result for the plant is mottled yellowing leaves and stems. A secondary infection of Black Sooty Mold is almost always to follow here in Houston. The Mealy Bug's excrement is sticky, and mold spores floating in our humid air land on this excrement where it can spread on leaf surfaces and stems.
So, how to get rid of the little guys? Neem Oil or All Season's Oil are the best organic sprays to control these unwanted visitors. Simply mix the oil to the ratio on the label, and spray all leaf surfaces and stems. Some extra caution needs to be used when using Neem Oil since the oil can burn the plant if tempratures are above 90 degrees F. To avoid chemical burn, spray plants in the early morning, or late in the evening, when the sun is low. Easy enough to do, right? But wait, we still aren't done! Repeat this same process 3-5 days after the first treatment, and again in 7 days after the second treatment. This will break the larval cycle, and ensure any "babies" hatching won't reinfest the plant again.
I like to follow up with Superthrive on all my "stressed" plants. Mix one capful to a gallon of water and pour it on the soil around the base of the plant. This extra kick of vitamins and hormones will give the plant the ummph it needs to shine once again!