Are insects attracted to colours or do some purple flowers have more nectar and pollen to attract insects in the first place?
Anne Bebbington quoted in Science and Plants for schools says ‘You need to take into account that different sorts of insects see colour differently. Most insects except for some butterflies do not see red well. Flowers may have colour which we can’t see but insects can e.g. ultraviolet markings.
Colour is not the only thing that attracts insects, scent e.g. is often important. Again it it is very likely that there are scents that we can not detect.’

According to my Lithuanian friends ‘If you keep bees, or if you would like to attract more of them into your garden, consider sowing lacy phacelia (Phacelia tanacetifolia Benth.), viper’s bugloss (Echium vulgare L.) and borage (Borago officinalis L.). In addition to their honey-producing properties, they also make an attractive addition to your border. Some attention should be given to caterpillars of butterflies. Plants in the pea family (clover, sweet clover), as well as the cruciferous plants (field penny-cress, shepherd’s purse, bitter cress, brassicas) are most appealing to caterpillars of beneficial insects.’ see more on mygarden.

Fpor more varieties of Purple flowers read or Purple patch