Insects' perspective..

..on a rainy day. Theoretically they could look upon the gray clouds (i.e. if they had such a good sight, which basically they don't) between the flowers and grass and weed ....and who knows if they (lets say a newly "emerged" butterfly who had its caterpillarbrain rearranged, or a mayfly that has only been around since that morning and has never seen a threatening sky) realize what is about to happen. 
But still there is something, like the change in atmospheric pressure that adverts them and makes them seek shelter!