The rain brought this small beetle out to feast on the rose petals. I’m not an expert, but this looks very much like a cucumber beetle (Diabrotica balteata) even though this photo was taken much further south than its supposed range as described on Wikipedia.
(Sony A65, ISO 1600, f/7.1, 60mm [90mm eq], 1/2000s)
This photo was taken in southern Brazil (around 28.5°S) in January of 2018.