|my hybiscus plant has a white powdery pest that looks like a fly on the underside of the leaves. I've tried stuff I'd normally use for aphids but can't get rid of this pest. What is it and what can I use to get rid of it?|
|I apologize for the delay in responding. We were flooded with questions and are working to catch up! Whiteflies are tiny, white insects that feed in large numbers on leaf undersides, sucking out plant juices. They secrete honeydew that may cause the growth of a sooty, black fungus on leaves. Their feeding can cause leaves to turn yellow and drop. They are easily disturbed and fly around when you brush against an infested plant. They are often found on hibiscus and ivy. Does that sound like your pest?
I always start with the simplest method first, and if that isn't successful, move on from there. A strong blast of water from the hose often works. Spray underneath leaves where they hang out. Do this daily if you notice insects.
Whiteflies are attracted to the color yellow. You can purchase or make yellow "sticky" traps from yellow cardboard smeared with petroleum jelly. They fly to it and get stuck.
Soapy water sprays are another possibility. Use 1 teaspoon to 2 tablespoons of liquid detergent soap per gallon of water. Use regular, not concentrated soap. Don't use soaps with lemon, as the citric acid can burn plants. Start with the lower amount and work up as needed. Spray as often as needed. As with any spray you might wish to test it on a few leaves first before you treat all your plants. Spray early in the morning before the sun heats up. Next on my list would be an insecticidal soap spray.
The insecticidal soaps are made from plant-derived fatty acids and target soft-bodied insects. There's really no way you can target the bad guys without fallout on the good guys. If you can regularly monitor and tolerate some damage to your plants, over time Mother Nature strikes a balance, with the beneficials coming in to control the bad guys. Healthy vigorous plants will withstand insect attacks best, and it's really the best thing you can do to prevent insect problems. Finally, whiteflies are temperature dependent. When weather cools, they disappear. I hope this information helps!