Sounds like aphids to me. Hidden Valley Hibiscus has a great web site with info about how to identify pests, and what to use to correct the situation. The first thing to do if it is aphids, is to spray your buds to remove the aphids. Knocking the aphids off with a spray of water actually will kill the aphid, as their probiscus (beak) is broken off in the process, and without that, they cannot eat. Also, check to see if you have ants. If so, place ant bait around the base of your hibiscus so you can control the ants. The ants will protect the aphids, and keep them going on your plant in order to harvest their secretions. The best product around to control aphids is Green Light Tree & Shrub with Safari. This product will cover all types of aphids, even a resistant variety that has developed here in California. Plus, it's super easy to use, and lasts 2 to 3 months. I would try to take some close up pics and post them, so we can actually take a look and help you identify the offending bug.

Patty S.

Here is a link that might be useful: Hidden Valley Hibiscus - Pest Control