My guess is that you sprayed the insecticide on a sunny day and this caused some leaf damage. I suggest you try to handpick or rinse off any insect pests while the plant recovers. I suspect you will be rewarded with some new growth later this season and a fresh start next spring. Your hibiscus will drop its leaves this fall and this plant takes a long time for new growth to resume in the spring so don't give up. Keep growing, Marianne Binetti