Shiny Leaf Sheen on Roses May Be Aphids Feeding

A. I think what you are seeing may be some residue from
some feeding insects on roses. These insects excrete (release) a sugary
substance from their feeding that falls on plant parts like leaves.

Aphids on unopened rose buds/flowers. They feed on plant sap. They use the sugars in plants sap as a food source for energy. The remaining sugars are excreted from the aphids where they cause a shiny sheen on leaves that is sticky. This attracts ants and bees.

If this is
what you are seeing it should be slightly sticky and may attract ants and bees
that will collect this residue for feeding. These insects pull out plant sap
that contains sugars for their own feeding and there is so much of it in the
plant sap that their excretion contains a lot of sugars. Insects that release
this kind of “honeydew” as it is sometimes called include aphids, scale
insects, leafhoppers and whiteflies. Roses aren’t the only plants these insects
feed on. We will seed them on most trees, shrubs and even pines.

Aphids on undersides of pepper leaves

Repeat applications of soap and water sprays will usually
control them until hot weather comes. High temperatures are not a good thing
for insects like aphids and help to keep them under control until the cool fall
weather sets in when we may see them again.