Beginner Gardening: no gardening experience - just bought a desert rose... HELP!, 1 by iriegirl

iriegirl wrote:
I recently bought a rather healthy desert rose from Home Depot. I have had them in the past & they always end up with these grey bugs that seem to kill the plant. So when I bought my most recent I asked for a insectiside to keep them away (i have tried soap & water to prevent bugs with no luck) . Before I applied the insectiside (Garden safe brand multi-purpose garden insect killer by Shultz) the Desert Rose was hearty with beautiful blooms & many buds, the day after I applied the insectiside, the blooms were brown & shortly after the leaves started to yellow. I rinsed the plant, but everyday more leaves are falling & the blooms & buds are completely gone. I have attached a pic of the evil insect. I would sooooooo appreciate any knowledge on this bug & a safe way to keep them away from my plants. Also any general suggestions on how to feed (if at all) the desert rose. Many thanks from sunny South Florida!!