The camera can't expose correctly for the whole shot because it contains a dark section which you were focussing on (and appears to have been dominant in determining the exposure the camera chose) and a bright section.  It can't get all of this in accurately so either the centre is exposed to see inside where the wasp is or the outside of the flower would be exposed correctly but inside the flower would look very dark.  

If you want the outside of the flower to be the correct colour/exposure then try focussing on that first, keep the shutter button half depressed and recompose the shot (ie move the camera back so that the bee is in the centre again). Then press the shutter button fully.

It also depends how you are metering the scene in the camera (spot metering based on one point of the scene or matrix metering based on the average lighting across the whole shot) since this makes a difference in how the camera determines the correct exposure.

Ad astra per aspera