Spider mites are a warm weather problem for several hibiscus growers. They thrive in hot, sunny, and dry conditions when temperatures are high. The first sign of spider mites is when a leaf or two get yellow mottling mixed in its normal green, then slowly the entire leaf turns bright yellow then falls off. Soon more and more leaves turn yellow and fall off, which can be fatal to your plants. As the spider mites spread, you can see very fine webbing at the tips of the branches with yellow leaves.
I've been battling with spider mites for the last 2-3 weeks. As a safe treatment, it was recommended to spray the underside of leaves with a hard stream of water at least once a week. This washes off the spider mites and breaks their lifecycle. However, this method has been ineffective on our large hibiscus plant, which has lost most of it's leaves due to spider mite damage. One by one, the leaves would yellow and fall off within 24 hours. Amazingly, the hibiscus was still blooming well during this time.
I also tried the use of beneficial insects, the Green Lacewing larvae. I received the eggs in the mail from http://www.arbico-organics.com. When I noticed some of the eggs had hatched inside the container, I sprinkled the eggs and live larvae onto the hibiscus plant. This method will reduce the number of spider mites if applied correctly.
I also researched Miticides that were proven effective. The two name brands I found most popular are Forbid 4F and Floramite SC, both of which kill the adult mites AND the eggs. Forbid 4F seems to be the stronger of the two, since it kills all kinds of mites. Forbid 4F offers knockdown and residual control of mites and whiteflies. The active ingredient in Forbid is spiromesifen. I purchased a 5mL bottle of Forbid 4F on eBay, which makes 8 gallons and is more than enough for a small volume grower.
Compare miticides such as Forbid & Floramite here :
Miticide Chart
