What insect or bug makes leaves a shiny white substance on my flowers?

Powdery mildew.

SLUGS! or SNAILS Powdery mildew isn't shiny. Use slug bait or beer in jar lids under a lightweight cover. check every morning http://www.instructables.com/id/Slug-Trap-from-Recycled-Water-Bottles/

http://homeguides.sfgate.com/bugs-leave-clear-sticky-liquid-plants-trees-26240.html

aphids

If its sticky its probably little critters called mealey bug, very small looks a little like tiny bits of cotton wool, need a bug spray, if its an indoor plant take it outside to spray it!

Pigeons :-)

Slugs !

If it's shiney,its slugs. If it's sticky,it's

Slugs!

First of all is it effecting the plant in anyway? Yes it does sound sound like it's snails and slug granules so sprinkle granules for snails and slug! U can find it at Walmart and hardware stores. first. You might also put some Sevin Dust over potting soil! Well good luck, hopefully this info will be helpful!

Thank u guys!

Thanks!