Question
have 3 mallow hibicus,,,first 3 yrs bloomed terrific...last year and this year    lots o blooms but they turned brown and dropped to the ground....i examine the buds and found tiny worms inside..i spray my garden every 10 days but worms still get inside buds..what do you think?

Answer
Bill,

It sounds like the tiny worms you are talking about are actually thrips which are very fond of flowers.  These tiny insects somehow get into even closed flower buds.

I would not spray your garden on a calendar schedule as this can lead to thrips resistance to insecticides.  This has happened in greenhouses and may have happened in your garden.

Take a sample to your local extension for confirmation and a preventative plan.

Good luck

Gary