Nature's attractions (Focus - July)

At this time of year, there are many varieties of purple and violet flowers in bloom, and these attract many insects, especially butterflies and bees. This preference appears to be related to the way that they see light. While we see light in the red/green/blue spectrum many insects see it in the blue green and ultraviolet (UV) range. As purple and violet flowers, such as meadow cranesbill and meadow clary, naturally reflect more UV light, they will stand out in a sward, making them easier to spot by the insects.
 
Not only do many plants have flowers of a similar colour, many of those flowers are similarly shaped. Brown, black and greater knapweeds all have slightly spherical flowerheads topped with a purple flower. These are tall, tough plants that can be found in great drifts in rough grassland and on roadside verges. Easily separated from knapweeds by their spines, thistle flowers are nonetheless quite similar. There are many different species of thistle, adapted to different environments and with varied shaped and sized flower heads. Some have large upright flowers, others smaller or drooping ones. But all are recognizable thistle-like, just variations on the classic Scottish thistle flower. Thistles and knapweeds are members of the daisy family, and their flowers are made up of numerous individual florets, so they are known as composites. After flowering, the white or buff coloured seed heads, called the pappus, provide food for small birds, such as Goldfinches. As well as providing a great source of nectar for insects, thistles are the food plant for the Painted Lady. This butterfly can complete its life cycle within 3 to 5 weeks, given the right conditions, and comes to this country as a migrant from the Atlas Mountains. As the butterflies head northwards, successive generations keep the migration going until, during the best years, they may get as far north as Iceland before the final generation heads south again, perhaps using winds at higher altitudes to help them.
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There are good numbers of Painted Ladies around at the moment, so we may be in for a bumper summer. Look out for them on garden buddleia - another purple flower attractive to butterflies. Indeed, many of the garden plants we plant to benefit pollinators – nepeta/catmint, lavender, asters, borage, salvias, alliums – have purple/lilac flowers. But that is just the day flying insects. Moths are more attracted to the flowers that show up in the dark – white and bright yellow – for example, nicotiana and evening primroses. As always, variety is the key, so there are no hard and fast rules about what will attract insects to your garden, but these days many plants and seed packets indicate whether they are pollinator friendly to help guide us.

Andrew Graham